Lung, breast, prostate, and colon cancers are the major causes of cancer deaths. If you want to live free of cancer, it is imperative that you develop
a prevention strategy against these major cancers, especially if you have a family history of any of them. By prevention, we mean three things:
Stopping your body's cells from becoming damaged in the first
Keeping any microscopic cancer cells that do appear from pro
gressing to life-threatening tumors
- Getting an accurate diagnosis early enough in the course of the disease to give yourself the best chance of a complete recovery
Lung cancer kills more Americans each year than any other form of cancer. In 2001, an estimated 150,000 people in this country died from the disease,
representing more than one-fourth of all cancer-related deaths. Each year, 14 percent of new cancer cases involve lung cancer. This is tragic, because lung
cancer is the most easily preventable form of the disease.
The epidemic of lung cancer over the last 100 years is due largely to tobacco use. There is no longer any debate about the issue: Smoking causes lung cancer.
For every 100 cases of lung cancer, 90 of them result from smoking. This is true whether you're talking about using cigarettes, cigars, or pipes. Even exposure
to smoke in the air-so-called environmental tobacco smoke or secondhand smoke-causes cancer.
The best way to prevent the disease? Simple: Don't smoke. If you do smoke, do everything you can to stop.
But what about the 10 percent of lung cancers that develop in people who don't smoke? What causes them? The main culprits appear to be two carcinogenic
(cancer-causing) substances, radon and asbestos.
Radon is a gas that results when molecules of uranium and radium decay. Invisible and odorless, radon can seep into houses. The Environmental Protection Agency
estimates that about 1 out of 15 homes in the United States has an unsafe level of radon. Many schools and businesses may also be affected. Each year, approximately
15,000 cases of lung cancer result from radon exposure.
Asbestos is a naturally occurring mineral complex that was once considered a miracle product because of its unique qualities. Specifically, its fibers can be woven
into lightweight, fire-resistant, and extremely strong materials. Asbestos was widely used for insulation in homes and office buildings until 1989, when it was
banned by the Environmental Protection Agency because of its cancer-causing effects. Asbestos was also common in shipbuilding and brake repair. Asbestos fibers
break easily into particles that can float in the air and stick to clothes. Inhaled particles lodge in the lungs, damaging cells and triggering the development
of cancer. Workers who have been exposed to asbestos, including those involved in its mining and manufacture, have 3 to 4 times the risk of lo. cancer. The risk is
even higher among asbestos workers who also smoke.
Detecting Lung Cancer
In the early stages, lung cancer causes no symptoms, so the best method for detecting it is regular yearly exams by your physician. See a physician immediately
if you have any of the following common signs and symptoms:
- A cough that doesn't go away and gets worse over time
- Constant chest pain
- Coughing up blood
- Shortness of breath, wheezing, or hoarseness
with pneumonia or bronchitis
- Swelling of the neck and face
- Loss of appetite or weight loss
Since a number of respiratory diseases cause similar symptoms, your doctor will take specific steps to determine what's causing the problem. You'll be asked
questions about your medical history, smoking history, and possible exposure to environmental carcinogens. The doctor will also perform a physical exam and may
order a chest x-ray and other tests. Even more sensitive than a chest x-ray in detecting lung cancer at an earlier stage is a spiral computed tomography (CT) scan.
The earlier cancer is found, the greater the chances for a cure. If you are at high risk for lung cancer, talk to your doctor about whether a spiral CT scan is an
If lung cancer is suspected, your doctor will order a lab test to study cells found in a sample of mucus from your lungs. If the results of this test known as sputum
cytology) are positive, you'll probably be asked to undergo a lung biopsy. A small sample of tissue will be removed for study under the microscope by a pathologist
trained in analyzing tumors.
Here's the good news: If you quit smoking now, it's possible for you to reduce your risk of lung cancer to the same level as that in people who never smoked.
Studies have found that ten years after quitting, an exsmoker's risk of dying from lung cancer is 30 to 50 percent less than the risk for those who continue to smoke.
After fifteen years, an ex-smoker's risk is almost the same as that of a person who never smoked. Quitting smoking also reduces the risk for developing heart disease,
emphysema, and cancers elsewhere in the body. You'll live longer, and you'll live better.
As physicians, we know that stopping smoking is not easy. We've seen many of our patients struggle to meet the challenge. There is no magic formula, but it can be
done. You may need several tries before you hit on the right strategy for you. Some of the natural approaches to support your effort to quit may help you.
According to several published studies, for many people the best strategy for quitting smoking may be to just stop to go "cold turkey. Nicotine-replacement therapy
(using gum, a skin patch, or an inhaled form) is effective for about 13 percent of people who try it. Behavioral modification (rewards and punishments) works for
about two people in every hundred. Acupuncture is only slightly better. Some people have been able to quit following hypnosis. Sad to say, in our experience, the
most successful aid to smoking cessation is hearing a doctor say, "You have lung cancer."
It is especially important to reduce smoking among youths, because younger lung tissue appears to be more sensitive to the cancer-causing effects of tobacco smoke.
We also know that preventing teens from smoking reduces their risk of becoming smokers later in life.
Environmental poisons cause lung cancer, and some people may be genetically vulnerable to these poisons. But your diet may be the key to whether you get cancer. If
two people with the same protective genes are exposed to the same level of pollutants, the one who follows a cancerprotective diet has a lower risk than the one who
eats junk food every day.
Here's an example. The rate of smoking among the Japanese is much higher than the rate in the United States, yet the Japanese have a lower incidence of lung cancer.
Research suggests that it's because they have more of the dietary factors that protect against cancer: a higher intake of soy, green tea, and fish and a lower intake
of dairy products and red meat.
The guidelines in Chapters 2 and 3 will help you with an effective lung cancer-prevention diet and supplement program. But there are some areas that you should try to
put even more focus on. For example as mentioned previously, one way to protect the body against toxins from smoke and pollution is to increase the intake of curries.
Curry dishes get much of their favor from a spice, turmeric. Turmeric's dis tinctive yellow color comes from a pigment called curcumin. In the body, curcumin acts as
an antioxidant and also aids in detoxification te actions. When you smoke or are exposed to secondhand smoke, cancer. causing compounds are taken in by the body,
metabolized, and eliminated through the urine. Adding turmeric to the diet helps the body to neutralize these toxic compounds more efficiently. It's as much as 300
times more effective than vitamin E. Curcumin also possesses other significant anticancer effects, as we'll discuss in Chapter 8.
Curry dishes are a delicious way to get healthy doses of curcumin. It's also available as a natural supplement. The recommended dose is 200 to
400 mg daily. An alternative supplement for lung cancer protection is to take quercetin (200 to 400 mg daily). Flavonoids like quercetin and those found in green
tea reduce the risk of lung cancer. A study published in the Journal of the National Cancer Institute looked at the diets of nearly 600 people living in Hawaii who had
lung cancer and compared them with diets in a matched group without cancer. The researchers discovered that people who ate the most apples, white grapefruit, and
onions--foods especially rich in quercetin-were 40 to 50 percent less likely to develop lung cancer.
Given the significant protection against lung cancer of the omega-3 fatty acids from fish consumption,25 we recommend, in addition to eating at least two
servings of cold-water fish per week, taking enough cap
Smokers should not supplement their diet with synthetic beta-carotene unless they also take a multivitamin containing the other key antioxidant nutrients:
vitamins C and E and selenium. Taking synthetic beta-carotenc alone and continuing to smoke may increase your risk of lung cancer. The best strategy to get the
protection of carotenes against lung cancer for smokers is to increase the intake of natural carotenes from food sources.
sules of a fish oil product to provide 120 to 360 mg of EPA and 80 to 240 mg of DHA daily for anyone at risk for lung cancer.
A long-term cancer prevention trial studied more than 1,300 patients with skin cancer and found that selenium appeared to reduce the rate at which new skin
tumors formed. The results were exciting, because they showed that simply adding a nutritional supplement to a normal diet could prevent cancer.
But what about other cancers? To find out, the researchers expanded their study, to that "gold standard" of scientific research: It was a randomized, double-blind
study, which means neither patients nor doctors know who is receiving the intervention. This minimizes the chances of a significant placebo effect. Patients took a
tablet containing either 200 mcg of selenium or a placebo daily for four-and-a-half years and were followed for an additional six-and-a-half years.
The outcome was so positive that the researchers stopped the trial two years sooner than planned. The overall cancer rate was significantly lower in the selenium
group than in the placebo group (77 cases versus 119). The selenium group had fewer lung cancers (17 versus 31), fewer colorectal cancers (8 versus 19), and fewer
prostate cancers (13 versus 35).
The results also showed that the death rate from cancer was 50 percent less in the selenium-treated group than the control group (29 versus 57). Lung cancer deaths
were lower in the selenium-treatment group than in the placebo group (12 versus 26). There was no significant difference between the two groups for other causes of
Clearly, selenium is a valuable part of the cancer-prevention strategy. As noted in Chapter 3, we recommend taking a vitamin and mineral supplement that gives you 100
to 200 mcg of selenium per day. In order to fully realize the benefit of any single antioxidant like selenium, it is important that it be taken with the other
important antioxidant nutrients.
For many women, breast cancer is the disease they fear most. The frightening statistic is that about one in seven or eight women will develop breast cancer in
their lifetime. Fortunately, there are many effective strategies that can help reduce your risk. One is to know the factors that can contribute to the disease.
Of course, lifestyle and diet are among the biggest factors that determine your risk of breast cancer. Here is a quick guide to the important risk factors.
The risk of breast cancer increases as a woman gets older. Breast cancer is uncommon in women under age 35. Most breast cancers occur in women over the age of 50,
and the risk is especially high for women over 60.
Breast cancer occurs more often in white women than among blacks, Hispanics, or Asian women.
A woman's risk for developing breast cancer increases if her mother, sister, or daughter had breast cancer, especially at a young age.
The presence of certain genes increases the risk of breast cancer, although this is mainly true if most or all of the women in your family have actually
developed breast or ovarian cancer. Women of Ashkenazi (central and eastern European) Jewish ancestry tend to have a higherthan-average rate of breast cancer.
The female hormone estrogen stimulates breast cells. The longer a woman is exposed to estrogen in any form (made by the body, taken as a drug, or
delivered by a patch), the more likely she is to develop breast cancer. For example, risk is higher among women who began menstruation at an early age
(before age 12), experienced menopause late (after age 55), never had children, or took hormone replacement therapy for long periods of time.
Women who have their first child after about age 30 have a greater chance of developing breast cancer than women who have a child
at a younger age. The most protection comes from childbirth followed by breast-feeding enough to suppress the return of ovulation.
Breast cancers nearly always develop in dense tissue (lobes and ducts), not in fatty tissue. That's why cancer is more likely to occur
in women who have "dense" breasts than in those with "fatty ones. Complicating the picture is that abnormal areas in dense breasts are harder to detect
on a mammogram.
Among the factors that have been linked to breast cancer in varying degrees are exposure to xenoestrogens (synthetic compounds that mimic estrogen),
secondhand smoke, pesticides, herbicides, power lines, electric blankets, radiation, and lack of exposure to sunlight.
Taking into account other established risk factors for breast cancer, women who regularly exercise have up to a 60 percent reduction in the risk of breast
cancer compared with women with low levels of activity.
Women who drink one drink a day have a 10 percent greater risk; those who drink two drinks have a 20 percent increased risk, and so on.
As with most other cancers, cigarette smoking increases the risk of developing breast cancer.
Important dietary factors include body weight (the more overweight you are, the greater the risk); increased intake of saturated fat;
and decreased intakes of antioxidants, dietary fiber, omega-3 fatty acids (particularly alpha-linolenic acid), and dietary phytoestrogens
(estrogen-like compounds found in foods such as legumes, nuts, and seeds).
Detecting Breast Cancer
Early detection of breast cancer improves the likelihood of preventing it from progressing to a life-threatening condition.
The earlier it can be detected, the better. Monthly breast self-exams are important steps toward this goal. But mammography (a special type of breast x-ray)
can detect breast cancer long before it can be felt. Most medical doctors, as well as the National Cancer Institute, recommend that women age 40 and older have
mammograms every 1 to 2 years.
Recently, however, this practice of routine mammography has come under fire. An increasing number of studies suggest that for women under 50 who have not yet
gone through menopause, screening mammograms may not be necessary. According to many experts in the field, screening mammograms don't work very well for these
They have a high rate of false negatives (results that show no can
cer when in fact cancer is present). The dense, healthy breast tissue of younger women can obscure tumors. Routine mammograms miss approximately 40 percent
of the breast cancers that
develop among women ages 40 to 49.
Mammograms expose women to radiation that may cause breast
cancer. With modern mammography equipment the risk is small (no more than 1 in 2.700). On the downside, the risk is cumulative, meaning that the chances
increase with each subsequent mammogram.
Screening mammography has not always been shown to increase the chances that premenopausal women will survive breast
cancer, even though it's been detected.
In women over the age of 50, it appears that mammography is best used to evaluate suspicious lumps rather than screen
for cancer (that is, to look for cancers when there is no sign the woman might have the disease). Results from a major study, The Canadian National Breast
Screening Study-2, involving nearly 40,000 women, showed that yearly mammograms in women 50 to 59 years old did not lower breast cancer mortality compared with
yearly physical examination alone. The authors of the study concluded that for women older than 50, thorough annual physical breast examinations, plus teaching
of breast self-examination, may be a valid alternative to yearly mammography.
A highly publicized report in the New England Journal of Medicine in early 1999 on the value of prophylactic mastectomy in women with
a family history of breast cancer raises many interesting questions. The retrospective study consisted of all women with a family history of
The debate about the value of regular mammograms has been heating up in recent years. Many women, understandably, are confused.
Before deciding on your approach to breast care, be sure you speak with your primary caregiver, gynecologist, or other qualified health expert. Be sure to
discuss your family history, lifestyle, and other issues to be sure you get advice that's right for you. In our clinical practice we have seen numerous women
who discovered during an annual mammogram breast cancer too small to feel with a self breast-exam. If a woman is at extremely low risk for breast cancer, it
may make sense to get mammograms every 2 to 3 years instead of annually to reduce the risk of radiation. If a woman has significant risk for breast cancer
because of family history of breast or ovarian cancer, however, then annual mammograms probably still make sense at this time.
breast cancer who underwent bilateral (both breasts) prophylactic mastectomy at the Mayo Clinic between 1960 and 1993. The women were divided into two groups--high
risk and moderate risk-on the basis of family history. A control study of the sisters of the high-risk women was used to predict the number of breast cancers
expected in these two groups if they did not receive a prophylactic mastectomy. The researchers identified 639 women with a family history of breast cancer who
had undergone prophylactic mastectomy of both breasts: 214 at high risk and 425 at moderate risk. The median length of follow-up was 14 years. The median age
at prophylactic mastectomy was 42 years. According to the Gail model, 37.4 breast cancers were expected in the moderate-risk group, but only 4 breast cancers
occurred. This difference correlated to an 89.5 percent reduction in risk. In high-risk women, breast cancer was diagnosed in 1.4 percent (3 of 214) of the
high-risk women who elected to have a mastectomy. In contrast, 38.7 percent of their 403 sisters were diagnosed with breast cancer (115 cases were diagnosed
before the respective sister's prophylactic mastectomy, 38 were diagnosed afterward, and the time of the diagnosis was unknown in 3 cases). What all of these
results indicate is that a prophylactic mastectomy was associated with a reduction in the incidence of breast cancer of at least 90 percent in these high-risk women.
Given the growing number of women who will now have a family history of breast cancer, do these results indicate that prophylactic mastectomy should be the primary
preventive measure for these women? It is hard to argue against the numbers, but prophylactic mastectomy seems to be a very aggressive preventive measure. Instead,
the focus should be on diet and lifestyle. In fact, it is estimated that dietary interventions alone could reduce the risk for breast cancer by at least 80 percent,
which is pretty close to the level produced with prophylactic mastectomy.
The Night Shift-Melatonin Breast Cancer Connection
Several studies have shown quite dramatically that women working the so-called graveyard shift have an increased risk of developing breast cancer. In fact, in one
study graveyard shift work was associated with a 60 percent increased breast cancer risk. The risk seems to be related to how much time was spent on the job
The explanation given for this link is that exposure to light at night appears to increase the risk of breast cancer by suppressing the normal nighttime production
of melatonina hormone secreted by the pineal gland (a small pea-sized gland at the base of the brain). The exact function of melatonin is still poorly understood, but
it is critically involved in regulating the natural biorhythm of hormone secretion referred to as the circadian rhythm. Melatonin exerts significant anticancer
effects and is described in more detail in Chapter 13.
Release of melatonin is stimulated by darkness and suppressed by light Nighttime exposure to bright light therefore suppresses melatonin manufacture and secretion.
To offset the increased risk of breast cancer with night shift work, we recommend taking 3 mg of melatonin at bedtime for night shift workers (regardless of when
that bedtime might be).
Breast Is Best
There's a special lifestyle factor that appears to offer some protection against breast cancer: breast-feeding. Several studies have shown that women who breast-feed
their infants for at least three months have a lower incidence of breast cancer. This may be because breast-feeding causes estrogen levels to fall, delaying
ovulation so the new mother won't get pregnant again too soon. Since estrogen is a known risk factor, any reduction in total estrogen exposure over the course
of a lifetime reduces the risk of breast cancer.
Of course, breast-feeding does the baby a lot of good too, Besides of fering wholesome natural nutrition, babies who are breast-fed have fewer and less severe
illnesses, they are less likely to have diarrhea, lower respiratory infections, car infections, and bacterial meningitis. Some research indicates that
breast-feeding may also protect against sudden in fant death syndrome, allergic diseases, and chronic digestive diseases.
Diet is one of the critical factors in the prevention of breast cancer. The research on diet and breast cancer is a bit muddy, because investigators often
look only to dietary factors in the United States. For example, let's take a look at the research on saturated fats and breast cancer. It is difficult to
determine true risk when looking at women in the United States, because the lowest percentile for saturated fat intake in the United States often translates
to the highest percentile in other countries. To gauge all dietary risk factors in breast cancer, it is extremely important to examine data from a global
perspective. In an extensive multinational population study, investigators explored diets from around the world to determine the components that most affect
breast cancer risk. The information
Dietary Factors in Breast Cancer
|FACTORS THAT MAY INCREASE RISK
|FACTORS THAT MAY LOWER RISK
|Soy and other legumes
collected provides much more valuable insight into dietary factors and breast cancer. Table 4-1 lists these factors in order of importance.
One of the most interesting aspects of the population study was the tremendous protective effect of fish consumption. Fish-particularly cold-water fish such as
salmon, mackerel, halibut, and herring-isa rich source of the omega-3 fatty acids. As described in Chapter 2 and elsewhere, this group of fats is very useful in
fighting against cancer, especially breast cancer. In contrast, the omega-6 fatty acids found in most animal products-as well as in common vegetable oils such as
corn, safflower, and soy-are associated with promoting breast cancer.
THE MOST IMPORTANT FOODS TO AVOID: MEATS GRILLED OR BROILED AT HIGH TEMPERATURES
It may not be simply that meat intake is associated with breast cancer. What may
eventually be shown is that the manner in which the meat is prepared determines whether it is carcinogenic. When broiled or grilled at high temperatures, meat
forms many potent carcinogens, including toxic lipid peroxides (especially those from alpha-linolenic acid) and heterocyclic amines. These compounds are extremely
harmful to breast tissue.
Researchers from the University of South Carolina gave questionnaires to 273 women who were diagnosed with breast cancer between 1992 and 1994 as well as 657 women
who were cancer-free. They found that women who routinely ate three meats-hamburger, beefsteak, and bacon-very well done had a 462 percent greater chance of
developing breast cancer. Women who regularly consumed these meats individually had lower increases in risk for breast cancer. The risk for very well done
versus rare or medium was 50 to 70 percent greater for hamburger and bacon, and 220 percent greater for beefsteak. These results, coupled with other evidence, suggest
that avoiding well done meats can dramatically
reduce breast cancer risk.
THE MOST IMPORTANT FOODS TO EAT: FISH, FLAXSEED, AND FLAXSEED OIL
The omega-3 fatty acids from fish have shown tremendous effects against breast cancer
in experimental and population based studies. In contrast, the omega-6 fatty acids found in most animal products as well as in common vegetable
oils such as corn, safflower, and soy-are associated with promoting breast cancer in experimental studies. The protective effect of fish intake against breast
cancer was thought to be due primarily to its high omega-3 fatty-acid levels.
In addition to a diet that features fish, eating ground flaxseed and supplementing the diet with flaxseed oil appear to offer significant protection against
breast cancer for a couple of different reasons. First of all, faxseed oil contains nearly twice the level of omega-3 fatty acids as fish oils, although it
is the smaller-chain alpha-linolenic acid rather than the longer-chain fats like EPA and DHA. Data derived from biopsies of adipose breast tissue at the time of
diagnosis from women with breast cancer compared with benign breast disease indicated that the relative risk of breast cancer for women in the highest breast
tissue level of alphalinolenic acid level was 64 percent less compared with those in the lowest level. In another study, the higher the level of alpha-linolenic
acid in breast tissue, the less likely the cancer was to spread into the lymph nodes of the armpit or to be invasive.
The second reason is that, besides containing high doses of alphalinolenic acid, flaxseed and flaxseed oil are the most abundant sources of lignans.
These components are fiber compounds that can bind to estrogen receptors and interfere with the cancer-promoting effects of estrogen on breast tissue.
Lignans also increase the production of a compound known as sex hormone binding globulin (SHBG). This protein regulates estrogen levels by escorting excess
estrogen from the body.
Population studies, as well as experimental studies in humans and animals, have demonstrated that lignans exert significant anticancer effects. In one recent
study, researchers followed 28 postmenopausal nuns for a year and tracked blood levels of two cancer-related estrogens: estrone sulfate and estradiol.
In addition to their normal diets, the nuns received daily supplements of 0,5, or 10 g of ground flaxseed. Estrogen levels fell significantly in the women taking
ground flaxseed, but they remained stable in the control group (those taking no flaxseed).
Ground flaxseed provides more nutritional benefits than does whole seed. That's because flaxseed is very hard, making it difficult to crack even with careful
chewing. But flaxseed is easy to grind in a coffee grinder, food processor, or blender. You can also buy FortiFlax from Barlean's at your local health food store.
This product contains ground flaxseed in a special nitrogen-flushed container for maximum freshness. Grinding makes flaxseed easier for the body to digest. We
recommend 1 to 2 tablespoons daily added to foods such as hot cereals, salads, or smoothies. We also recommend 1 tablespoon flaxseed oil daily. Flaxseed oil can
be used as a salad dressing or for dipping bread, or it can be mixed with yogurt or cottage cheese.
Paul Gross, director of the breast cancer prevention program at the Princess Margaret Hospital and the Toronto Hospital, has reported that flaxseed in the diet may
shrink breast cancers. His study involved 50 women who had recently been diagnosed with breast cancer. While waiting for their surgery, the women were divided into
two groups. One group received a daily muffin containing 25 g (a little less than 2 table spoons) of ground flaxseed. The others were prescribed ordinary muffins.
After surgery, the investigators found that women who had received the flaxseed muffins had slower-growing tumors than the others.
Don't cook with flaxseed oil
Don't cook with flaxseed oil Flaxseed oil has high levels of polyunsaturated fats, which can be damaged by heat. Never cook with flaxseed oil use olive or canola
oil instead. Buy flaxseed oil in small, opaque bottles and keep it refrigerated at all times. Some manufacturers also add antioxidants, such as vitamin E or rosemary,
to the oil to further protect it. Put a label indicating the date of purchase on the bottle. If the oil is not used within three months, throw it out and replace it
with a fresh bottle. Also dispose of any flaxseed oil that has a bitter or rancid taste.
Soy: It's interesting to note that among Japanese women (living in Japan), the rate of breast cancer is about one-fifth the rate in the United States.
When Japanese women move to the West, however, the rate increases, until by the third generation after immigration, the risk of breast cancer is about
the same. Researchers explain this rise by noting that most "Westernized" Japanese begin eating the standard American diet (high-fat, low-fiber, not enough
fruits and vegetables).
One reason might be that Japanese women eat much more soy than Westerners do. Soy is gaining in popularity. Since the 1970s, there has been a marked increase
in the consumption of traditional soy foods, such as tofu, tempeh, and miso, and in the development of so-called second-generation soy foods that simulate
traditional meat and dairy products. Consumers can now find soy milk, soy hot dogs, soy sausage, soy cheese, and soy frozen desserts at their grocery stores.
One of the big reasons for the increase in soy consumption is that there is now considerable evidence from laboratory and human studies that indicates a possible
anticancer effect of soy, particularly in hormone-sensitive cancers such as breast and prostate cancers.
- act as antioxidants
reduce estrogen levels, particularly free estrogen (Lower levels
of estrogen have been associated with a decreased risk of breast cancer.)
- prevent the formation of new blood vessels, thus preventing tumors from obtaining he blood supply necessary for continued growth
- prevent tumor cells from dividing and growing by inhibiting enzymes involved in cell replication
Population studies have consistently found that soy consumption may help reduce a woman's risk of developing breast cancer. Clinical and experimental
studies further support the benefits of soy. Such studies show, for instance, that when healthy women add soy products to their diets, their levels of
estrogen and other hormones fall. They also have lower levels compared with women who do not eat soy.
In recent years, growing evidence suggests that two isoflavones found in soy-daidzein and genistein-are the sources of soy's benefits. That's because
these substances act as phytoestrogens, naturally occurring plant compounds that bind to estrogen receptor sites in human cells, including breast cells.
By blocking these receptors, they reduce the effects of estrogen.
The amount of soy found to be protective against the development of breast cancer delivers 25 to 100 mg per day of isoflavones. We strongly recommend getting
this amount from foods rather than from dietary supplements of purified isoflavones. Many soy foods now state the level
Soy Foods and Isoflavone Content
|APPROXIMATE ISOFLAVONE CONTENT
|Roasted soybeans (soy nuts)
| 1/2 cup
of isoflavones per serving. As you can see from Table 4-2, you do no need to eat huge amounts of soy foods to meet the recommended levels.
New evidence suggests that soy contains other substances besides isoflavones that provide even more benefit. Researchers at the University of Chicago
tested soy on lab animals with mammary gland tumors One group of animals received pure soy protein (without isoflavones). another group got pure isoflavones,
and a third group got a mix that had both. All three groups had fewer tumors than the untreated animals. Surprisingly, the treatment that worked best was soy
without isoflavones. Clearly, something else is at work.
the greatest bene of soy consumption may occur during adolescence.studies indicate that preadolescent intake of soy enhance the maturation(differentiation) of breast
cells. these more mature cells are
Women who have estrogen-sensitive breast tumors should restrict soy intake and should avoid soy isoflavone supplements. Studies in test tubes and in animals
show that the isoflavone genistein stimulates growth of estrogen-receptor positive tumors. It inhibits the growth of breast cancer cells that lack estrogen
receptors, however. Whether these results apply to humans is not yet clear, but until more information is available it makes sense that women who have
estrogen-receptor positive breast cancer should restrict soy intake (no more than four servings per week) and should avoid soy isoflavone supplements.
less susceptible to carcinogens. The anticancer effects of soy intake after adolescence appear to be more valuable in preventing the onset of cancer
in the premenopausal women through more favorable estrogen levels and metabolism. The take-home message: Start eating soy as a child or, at the latest,
CABBAGE FAMILY VEGETABLES
Cabbage family vegetables include cabbage, broccoli, cauliflower, and kale. These flavorful foods, also called cruciferous vegetables,
contain anticancer phytochemicals known as glucosinolates. The most important of these is indole-3-carbinol (13C), a compound formed when the vegetables are
crushed or cooked. 13C and other glucosinolates are antioxidants and potent stimulators of natural detoxifying enzymes in the body. Studies have shown that
increasing the intake of cabbage family vegetables or taking 13C as a dietary supplement significantly increases the conversion of estrogen from cancer-producing
forms to nontoxic breakdown products.Thus 13C is thought to be especially protective against breast and cervical cancers.
To help you understand how this works, here's a quick lesson in biochemistry. The body breaks down estrogen in several ways. Some estrogen is converted into a
substance called 16-alpha-hydroxyestrone, a compound that promotes breast tumors. Another method of breakdown produces 2-hydroxyestrone, which does not stimulate
breast cancer cells. Increasing the intake of cabbage family vegetables or taking supplements containing 13C shifts the ratio so that your body produces more of
the "good" estrogen breakdown product and less of the "bad."
In high-risk women, we recommend either eating four to five servings of cabbage family foods per week or supplementing the diet with 13C at a dosage of 200 to 400 mg
daily. No side effects or drug interactions have been reported with 13C supplementation. Broccoli sprouts have been reported to have the highest levels. In terms of
glucosinolates, 1 pound of broccoli sprouts equals 40 pounds of fresh broccoli.
One of the key ways in which the body gets rid of estrogen is by attaching glucuronic acid to the estrogen in the liver and then excreting
this complex in the bile. Bacteria in your body also produce an enzyme called glucuronidase, however, which breaks the bond between estrogen and glucuronic acid.
When that happens, the level of estrogen rises. Not surprisingly, excess glucuronidase activity is associated with an increased risk of cancer particularly
estrogen-dependent breast cancer. The activity of this enzyme is higher in people whose diet is
high in fat and low in fiber. High glucuronidase activity may be one of the key underlying factors explaining why certain dietary factors cause breast cancer
and why other dietary factors are protective.
Glucuronidase activity can be reduced by eating lots of plant foods, especially onions and garlic and foods high in glucuronic acid, such as apples, Brussels
sprouts, broccoli, cabbage, and lettuce. You can further reduce glucuronidase by supplementing the diet with the "friendly bacteria" Lactobacillus acidophilus
and Bifidobacterium bifidum. For more information, see the section on probiotics in Chapter 3.)
Another option for inhibiting glucuronidase activity is to use a supplement called calcium d-glucarate. Researchers at major cancer centers are studying this
natural substance as a possible preventive measure in women at high risk for breast cancer. In the animal studies, calcium d-glucarate reduced glucuronidase
levels by over 50 percent, resulting in a drop in blood estrogen levels of over 20 percent and a 50 to 70 per cent reduction in mammary cancer. The recommended
daily dose for prevention is 200 to 400 mg; higher doses (400 to 1200 mg) may be necessary for individuals with existing cancer. There are no known side effects
or drug interactions.
The prostate is a single, doughnut-shaped gland about the size of a walnut that lies below the bladder and surrounds the urethra (the tube that connects the bladder
to the tip of the penis). The prostate secretes a thin, milky, alkaline fluid that lubricates the urethra to prevent infection and increases the ability of sperm
There are two main conditions that affect the prostate. One is prostate enlargement, also called benign prostatic hyperplasia (BPH). Almost every man will develop
an enlarged prostate if he lives long enough. BPH is not cancer and is not life-threatening, but it can cause symptoms such as difficulty urinating and disturbed
sleep. Treatment includes removing part or all of the prostate to improve urination.
The other condition, prostate cancer, is much more serious. It can cause symptoms similar to those in BPH, but it can also spread to other parts of the body and
can be fatal. In men, prostate cancer is the second leading cause of death due to cancer. (Lung cancer is by far the first.) Prostate cancer is a hormone-sensitive
cancer that will affect at least 1 out of every 6 men now living in the United States. Each year roughly 200,000 men are diagnosed with the disease in the United
States, and more than 30,000 will die from it. Because prostate cancer is a very slow-growing disease, however, it is not always life-threatening. About 30 percent
of men over 50 have signs of prostate cancer, but the disease is only fatal in about 3 percent of cases. Many men opt not to have treatment immediately after their
diagnosis but rather to wait and see what happens. That's why it's often said that many men die with prostate cancer rather than because of it.
In the united states ,prostate cancer is found mainly in men over age 55;more than 8 out of men with prostate cancer are over 65. the average age of
patients at the time of diagnosis is 70.
Family history of prostate (or breast) cancer:
A man's risk for developing prostate cancer is increased twofold if his father has had the disease and fivefold
if his brother has been affected. The risk increases twofold if both his mother and his sister have had breast cancer.
Prostate cancer is roughly twice as common in black men than in white men. It is less common in Asian and American Indian men.
Testosterone excess is thought to stimulate hormonedependent prostate cancer in much the same way that estrogen stimulates breast cancer. Other
hormones implicated are estrogen, prolactin insulin, and IGF-1.
Early studies found that prostate cancer develops up to twice as often in men who have had a vasectomy (surgery to make a man infertile), but more
recent studies have found no difference in prostate cancer risk.
Current research indicates that diets high in red meat and saturated fat are associated with an increased risk of developing prostate cancer. Risks are
also increased for those who have diets low in fruits, vegetables, phytoestrogens, selenium, vitamin E, lycopene, and other dietary antioxidants.
Men who gradually lose their hair at the front
The Bald Truth
According to a study of 4.000 men conducted by the National In stitutes of Health (NIH), male pattern baldness is associated with a higher risk of prostate cancer.
That's because both conditions involve the body's reaction to testosterone, the primary male hormone. Receptors for testosterone are found on hair follicles as well
as the prostate Male-pattern baldness has been linked to a higher risk for heart disease as well.
These findings do not mean that balding men will definitely get prostate cancer, only that they are at increased risk. Such men are advised to be more aggressive
in following dietary and supplementation programs to reduce their risk of developing prostate cancer.
and/or crown of the head, beginning in their mid-twenties, are 50 percent more likely to develop prostate cancer (see the box above).
Detecting Prostate Cancer
Early prostate cancer often does not cause symptoms. When symptoms do occur, they include any or all of the following:
- A need to urinate frequently, especially at night
- Difficulty starting urination or holding back urine
- Inability to urinate
Weak or interrupted flow
- Painful or burning urination
- Difficulty in having an erection
- Painful ejaculation
- Blood in urine or semen
Frequent pain or stiffness in the
lower back, hips, or upper thighs
These symptoms are not specific to prostate cancer. The first four, especially, are also typically seen in cases of BPH. The latter symptoms can
also result from prostate infections. If you are experiencing any of these symptoms, it is important to see a doctor immediately. The most important aspect
in detecting prostate cancer for men over age 50 (for blacks. age 45) is seeing a physician for an annual physical exam that includes a digital rectal exam (DRE)
and a blood test. During the DRE, the doctor inserts a lubricated, gloved finger into the rectum and feels the prostate through the rectal wall to check for hard or lumpy areas.
The blood test checks the level of a protein called prostate-specific antigen (PSA). Usually PSA is elevated in men who have prostate cancer, but approximately 35
percent of men with diagnosed prostate cancer will have a "normal" PSA (less than 4). Currently experts are debating whether this normal level should be lowered.
Until more research is done, our recommendation at this time is to have the test done annually and watch for a change.
A newer test that measures the activity of an enzyme called telo merase, found in the semen, may be more sensitive as a screening tool for prostate cancer. At this
time, the test is still being developed, but if research continues to prove its value, it may be available within a few years. Telomeres are like a "tail"on DNA.
Each division of the cell shortens the telomere, and when it reaches a certain size the cell will no longer divide. Cancer cells bypass this control by using
telomerase, which prevents the shortening of the telomeres and allows a cell to undergo unlimited divisions.
While prostate cancer is associated with many of the same lifestyle factors associated with other cancers, the connections are not as strong or consistent as
they are for breast or lung cancer. Nonetheless, it is important to engage in a healthy lifestyle by avoiding tobacco smoke and excessive intake of alcohol,
while engaging in a regular exercise program in order to reduce the risk of prostate cancer.
There is so much convincing evidence on the role of diet in prostate cancer that William Fair and his colleagues from the Memorial Sloan Kettering Cancer Center
suggest that prostate cancer may be considered a "nutritional disease".The prime suspects are diets that are
high in animal foods, particularly grilled and broiled meats (which
are high in heterocyclic amines); saturated fat; and dairy product
low in protective nutrients, such as lycopene; selenium; vitamin
E: soy isoflavonoids and other dietary phytoestrogens; omega-3 fatty acids (particularly those from fish); and isothiacyanates from cabbage family vegetables
As is true of breast cancer, these dietary factors are known to affect sex hormone levels, detoxification mechanisms, and antioxidant status. The following are
some additional points to be aware of.
One of the most important anticancer nutrients is lycopene, a carotene that provides the red color to tomato products. Lycopene is one of the major carotenes
in the diet of North Americans and Europeans. More than 80 percent of lycopene consumed in the United States comes from tomatoes, although apricots, papaya,
pink grapefruit, guava, and watermelon also contribute.
The amount of lycopene in tomatoes can vary significantly, depending on the type of tomato and how ripe it is. In the reddest strains, lycopene concentration is
close to 50 mg per kilogram (mg/kg), compared with only 5 mg/kg in the yellow strains. Lycopene appears to be relatively stable during cooking and food
processing. In fact, you actually absorb up to 5 times as much lycopene from tomato paste or juice than you do from raw tomatoes, because processing "liberates more
lycopene from the plant's cells. Eating a lycopene source with oil, such as olive oil, can also improve its absorption. That's one reason why a Mediterranean diet
(such as the Italian diet) has so many healthful properties.
Because lycopene is a more potent scavenger of oxygen radicals than other major dietary carotenes, it exerts additional anticancer effects, Recently Harvard
researchers discovered that of all the different types of carotenes, only lycopene was clearly linked to protection against prostate cancer. The men who consumed
the highest levels of lycopene (6.5 mg per day) in their diet showed a 21 percent decreased risk of prostate cancer compared with those eating the lowest levels.
It was also found that the high-lycopene eaters had an 86 percent decreased risk of prostate cancer (although this did not reach statistical significance, because
of the small number of cases). In a study of patients with existing prostate cancer, lycopene supplementation (30 mg per day) was shown to slow tumor growth,
shrink the tumor, and lower the level of PSA (discussed in more detail below).
In addition to prevention of prostate cancer, population-based studies also indicate that lycopene protects against cancers of the colon, cervix, lung, and breast.
As a bonus, researchers have also found a statistically significant association between high dietary lycopene and a lower risk of heart disease.
While lycopene has clear benefits, it is important to point out that in a test tube study it was found that lycopene alone was not very effective at stopping prostate
cancer tumors from growing. However, adding alpha-tocopherol resulted in a 90 percent decrease in cell proliferation. This result implies that lycopene works best
(and perhaps only) if vitamin E levels are sufficient.
Increasing your intake of lycopene is a key goal in preventing many cancers. Although lycopene supplements are available in pill form, they are relatively expensive,
especially when compared with food sources.
In short, the cheapest and healthiest way to boost lycopene levels is through diet. Foods rich in the important carotenes will also be high in vitamin C and other
antioxidants, but if you are at high risk for or currently have prostate cancer, then we definitely recommend supplementing your diet with an additional 30 mg of
Lycopene supplementation appears to have therapeutic protential in
prostate cancer. Twenty-six men with newly diagnosed, clinically localized prostate cancer were randomly assigned to receive 15 mg of lycopene twice daily
or no supplementation for 3 weeks before surgical removal of the prostate. Blood levels of PSA decreased by 18 percent in the lycopene group, whereas they
increased by 14 percent in the
control group not receiving lycopene. These results suggest that licopene supplementation (30 mg daily) may decrease the growth prostate cancer.
FAT INTAKE, BLACK MEN, AND PROSTATE CANCER
Black men develop prostate cancer twice as frequently as white men. Although we netics play a role, dietary differences also are involved. In a study conducted
by the National Cancer Institute of men who had been newly diagnosed with biopsy-proven prostate cancer and matched controls without prostate cancer, it was shown
that increased consumption of foods high in animal fat was more often linked to prostate cancer (inde pendent of intake of other calories) in black men than in white.
The higher the intake of animal fat, the greater the risk for advanced prostate cancer."2 Reducing fat from animal sources in the diet could lead to substantially
decreased incidence and mortality rates for prostate cancer, particularly among American blacks.
The isoflavones of soy, genistein, and daidzein exert significant protection against prostate cancer, according to population-based studies. Test tube and animal
studies have confirmed that soy isoflavonoids significantly inhibit growth of prostate cancer cells. 43 Since both testosterone dependent and testosterone-independent
prostate cancer cells are inhibited. it appears that soy isoflavonoids act against cancer in several ways. As is the case with breast cancer, the high intake of soy
may be one of the key protective factors accounting for the low rate of prostate cancer in Japan and China compared with other parts of the world. Studies show that
the blood and urine concentrations (an indicator of intake) of soy isoflavonoids were found to be 7 to 110 times higher in Japanese men consuming a traditional
Japanese diet compared with Finnish men consuming a typical Western diet. A study of 12,395 male Seventh-Day Adventists (who generally eat a healthy diet and
abstain from alcohol) found that those who drank soymilk had a 70 percent reduction of the risk of prostate cancer." All together, studies conducted in 42
countries confirm that soy is one of the most important dietary factors for protection against prostate cancer.
OMEGA-3 FATTY ACIDS AND PROSTATE CANCER
Considerable evidence indicates that the risk of prostate cancer is reduced with higher intakes of the omega-3 fatty
acids cicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both derived from fish. To more accurately determine the degree of protection, researchers in New
Zealand measured the level of EPA and DHA in red blood cells in a populationbased study." A high content of EPA and DHA was associated with a significantly reduced
prostate cancer risk. This study confirmed findings from previous population-based and lab studies showing that these omega-3 fatty acids inhibit prostate cancer
cells from growing. In addirion to eating at least two servings of cold water fish per week, we recommend taking enough capsules of a fish oil product to provide
at least 120 to 360 mg of EPA and 80 to 240 mg of DHA per day for anyone at risk for prostate cancer.
FLAK ABOUT FLAXSEED
While the evidence clearly indicates that the risk of prostate cancer is reduced with the intake of EPA and DHA, there is conflicting
with alpha-linolenic acid (ALA)—the omega-3 fatty acid found in flaxseed oil. Some studies indicate that ALA may actually increase the risk of prostate cancer.
In some of these studies, however, ALA intake was used simply as a marker for meat intake. If no vegetable sources of ALA, such as flaxseed or canola oil,
are consumed, the primary dietary source is from meat--the greater the meat intake, the higher the ALA tissue level. It is also possible that deficiencies of zinc
or other nutrients involved in the conversion of ALA to EPA are ultimately responsible for the elevations in ALA noted in men with prostate cancer.
No one has actually looked at the effect of flaxseed oil in prostate cancer, but ground flaxseed appears to be quite helpful not only in preventing prostate cancer
but also in men with existing prostate cancer (discussed in greater detail below). In addition to the phytoestrogen effect, flaxseed lignans bind to male hormone
receptors and promote the elimination of testosterone.
Until the issue with ALA and prostate cancer is resolved by more careful studies, we recommend that men should avoid flaxseed oil and instead focus on consuming
ground flaxseed and getting their omega-3 oils from fish and fish oil supplements.
Ground flaxseed also appears to be quite helpful not only in preventing prostate cancer but also in the treatment. In a study conducted at the Duke University
Medical Center and Durham Veterans Affairs Medical Center involving men with prostate cancer, a low-fat diet (in which represented no more than 20 percent of total
calories) supplemented with 30 g of ground flaxseed (roughly 2 tablespoons) reduced serum testosterone by 15 percent, slowed the growth rate of cancer cells, and
in creased the death rate of cancer cells after only 34 days.
Several population studies have suggested that vitamin E supplementation prevents prostate cancer. The same sort of protection has been demonstrated in
clinical studies as well.
In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study more than 29,000 male smokers ages 50 to 69 from southwestern Finland were randomly assigned to
receive vitamin E (50 mg), betacarotene (20 mg), both nutrients, or a placebo daily for 5 to 8 years (median, 6.1 years). Researchers found 246 new cases of
prostate cancer and 62 deaths from the disease during the follow-up period. A 32 percent decrease in the incidence of prostate cancer was observed among the
subjects receiving vitamin E compared with the men who did not receive it. Mortality from prostate cancer was 41 percent lower among men receiving vitamin E.
In the subjects receiving beta-carotene alone, rates of prostate cancer incidence and mortality were 23 and 15 percent higher, respectively, compared with the
group that did not receive this treatment. These findings are consistent with the study's other main finding that lung cancer rates were higher in the group
receiving betacarotene alone (see page 73).
The main point is that antioxidants must be taken as a group-not singly--so that they can work together. Taking vitamin E alone for cancer prevention is not wise.
It should be taken with the other important antioxidant nutrients, such as vitamin C, selenium, and zinc. That is why we stress the importance of taking a
high-quality multiple vitamin and mineral formula.
In a study conducted in Washington County, Maryland, nearly 10,500 male residents donated blood and toenail samples for a specimen bank. Toenail and plasma
samples were assayed to measure selenium, alphatocopherol, and gamma-tocopherol in a total of 117 of 145 men who developed prostate cancer and 233 matched
control subjects. Researchers found that the higher the concentrations of alpha-tocopherol, the lower the risk of prostate cancer. Men whose levels of
gamma-tocopherol were in the top 20 percent had one-fifth the risk of prostate cancer of the
men in the bottom 20 percent. Selenium was also found to be protective. The highest level of protection, however, was found among those men who had high levels
of all three compounds. The conclusion: To achieve the greatest degree of protection, use natural mixed tocopherols that include both alpha- and gamma-tocopherol,
not alpha-tocopherol alone. And take selenium as well as the other anticancer nutrients, according to the guidelines given on pages 312 and 313.
Selenium supplementation appears to be critically important in reducing prostate cancer risk. In a double-blind study of 974 men, selenium supplementation
produced a significant (63 percent) reduction in the development of prostate cancer compared with the placebo group. Because the results from this study and other
preliminary studies with vitamin E and selenium were so convincing, various follow-up studies with larger groups of men are now in progress. For example, the SELECT
Prostate Cancer Prevention Trial—the largest trial of its kind to date-began enrolling patients in July 2001. SELECT (which stands for Selenium and vitamin E Cancer
Prevention Trial) will determine whether these two dietary supplements can protect against prostate cancer. Sponsored by the National Cancer Institute, the study
will recruit more than 32,000 men over the age of 55 at more than 400 study sites in the United States, Puerto Rico, and Canada.
It will be many years before the results from this large study are available, but we believe that the existing evidence for supplementing the diet with these
nutrients already indicates that they are of value and should be used according to the guidelines given.
Cancer of the colon (large intestine and rectum) is the major cancer of the gastrointestinal tract. Colon cancer makes up only 15 percent of all cancers,
but it's the number-two cause of cancer deaths in the United States. The American Cancer Society estimates that there will be nearly 140,000 new cases of
colon cancer each year in the United States and that roughly 50,000 Americans will die from the disease. The good news is that the death rate from colorectal
cancer has been going down
for the past 20 years because of better early detection and improvedtreatment.
The risk factors for colon cancer are very similar to those of the other cancers in this chapter.
Colorectal cancer is more likely to occur as people get older About 9 out of 10 people with colorectal cancer are age 50 or older, but the disease can
occur in high-risk people in their twenties.
First-degree relatives (parents, siblings, children )of a person who has had colorectal cancer are somewhat more likely to develop colon cancer
themselves, especially if the relative had the cancer before the age of 50.
Polyps are overgrowths of cells on the inner wall of the colon and rectum. Some types of polyps increase the risk of colorectal cancer.
A condition known as hereditary familial adenomatous polyposis leads to the development of thousands of polyps in the large intestine. There's a very high risk
that one or more of these polyps will convert to a cancerous form.
Dietary factors are thought to be responsible for 80 to 90 percent of all colon cancer. A diet high in animal fats and heterocyclic amines from grilled or
broiled meats can increase the risk of colon cancer. Most studies on the benefits of fruits, vegetables, and fiber show a protective benefit, but others do not.
Multivitamins with folic acid, vitamin E, and calcium supplements appear to offer significant protection.
Inflammatory bowel disease:
Ulcerative colitis or Crohn's colitis is characterized by severe inflammation of the colon over a long period of time and is associated
with an increased risk for colon cancer. People who have chronic inflammatory bowel disease for 20 years or more have a colon cancer risk of almost 1 in 5.
History of prior pelvic irradiation:
Those who have been treated with radiation to the large intestine (for conditions such as prostate cancer, for example) are at
higher risk for colon cancer resulting from radiation damage to colon cells.
Smokers are 30 to 40 percent more likely than nonsmokers to die of colon cancer.
Being very overweight increases a person's colorectal can
Detecting Colon Cancer
Colon cancer screening should be part of your annual physical if you are over age 40, have a family history of colon cancer, or have any symptom suggestive of
- A change in bowel habits
Diarrhea, constipation, or feeling that the bowel does not empty
- Blood (either bright red or very dark) in the stool
- Stools that are narrower than usual
- General abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)/li>
- Weight loss with no known reason
- Constant tiredness
Anemia (Any case of unexplained iron-deficiency anemia must be
examined to rule out colon cancer.)
Vomiting, especially if associated with lack of bowel movements,
as this might suggest intestinal obstruction
Early detection of colon cancer usually includes one or more standard tests:
fecal occult blood test (FOBT) screens for hidden blood in the
stool (feces). Sometimes cancers or polyps can bleed, and FOBT is used to detect small amounts of bleeding, FOBT can identify
about 25 percent of patients with colorectal cancer.
is an examination of the rectum and lower colon
(sigmoid colon) using a lighted instrument called a flexible sigmoidoscope. The problem with this test is that the device does not examine the entire colon.
Your large intestine is shaped like an upside-down U. A sigmoidoscope can't "see around the corner" into the upper part, so it misses any polyps or cancers
in those regions, where approximately 30 percent of cancers occur. Flexible sigmoidoscopy and FOBT, when used together and perform only once, will miss about a quarter of patients with precancer colon polyps or invasive cancer.
Combining FOBT with sigmdoscopy identifies about 3 out of 4 patients with colorectal cancer.
which uses a lighted instrument called a colonie
scope, is more thorough because it can view the entire colon. I the most sensitive screening test for colon cancer (that is, it is mo likely to find cancer
if it exists), but it's also the most expensive
barium exam is also considered adequate for
screening. The problem with this test is that any suspicious areas cannot be sampled for a biopsy, so a colonoscopy is ultimately needed anyway if a possible
lesion is found.
We recommend that people who have any family history of colon cancer or who experience any symptom that suggests colon cancer get a colonoscopy. For people
without risk factors who are age 50 or older, we recommend a yearly FOBT, a sigmoidoscopy every five years, and a colonoscopy every ten years.
Lifestyle risk factors for other cancers apply to colon cancer as well, especially high alcohol intake. In regard to exercise, the association between
low physical activity and colon cancer has become one of the most consistent findings in large population studies for this disease. Well over a dozen studies have
now demonstrated this association. In an evaluation of over 47,000 men enrolled in the Health Professionals Follow-up Study, regular exercise was associated
with a nearly 50 percent reduction in colon cancer risk.
Dietary factors are thought to be the underlying cause of colon cancer in nearly 9 out of 10 cases. Countries where people eat a Western diet have up to 10 times
the rate of colorectal cancer compared with coun
tries that follow an Asian dier. Not surprisingly, diets high in animal fats and heterocyclic amines are particularly dangerous, while diets high in fruits,
vegetables, and fiber show a protective benefit in most (but not all) studies.
Diet has both direct and indirect effects. By direct effects, we mean that cells of the colon can be damaged when they come into contact with components of meat,
particularly heterocyclic amines and saturated fat. By the same token, the intestines can also receive direct protection by coming into contact with antioxidants.
Indirect effects are a sequence of events set in motion throughout the body by a poor diet or a malfunctioning digestive system. For example, incomplete protein
digestion or poor intestinal absorption of protein leads to the formation of polyamines, compounds that can dramatically stimulate cancer cell growth. Be sure to
take the self-evaluation on page 46 to determine whether you may be suffering from incomplete protein digestion.
Bacteria in the gut are thought to play a central role in colon cancer. Health-promoting bacteria, such as lactobacillus, bifidobacteria, and propionibacter species,
increase your body's ability to produce substances that protect you against colon cancer. These include short-chain fatty acids (SCFA), such as acetic, proprionic,
and butyric acid. When it comes to these compounds, the more the merrier: the higher the level of production, the greater the protection. For your body to produce
these, three criteria must be met:
There must be sufficient quantities of health promoting bacteria
in the gut.
- The diet must be low to moderate in terms of meat consumption.
- The diet must be sufficient in dietary fiber.
• There must be sufficient quantities of health promoting bacteria
in the gut. • The diet must be low to moderate in terms of meat consumption. • The diet must be sufficient in dietary fiber.
A diet consisting mainly of animal foods and refined sugars and lacking fiber will lead to the predominance of bacteria that break down proteins through a process
called putrefaction. In contrast, a healthy diet (plenty of fruits and vegetables, minimal meat consumption, lots of fiber) will result in an abundance of the
bacteria that specialize in the breakdown of fiber through fermentation.
The most important SCFA for protection against colon cancer is butyric acid (butyrate). Even at extremely low concentrations, butyrate profoundly suppresses
cell proliferation in cancerous cells. In test tube studies, butyrate stops the growth of cancerous colon cells, promotes apoptosis, inhibits the effects of
tumor promoters, and causes colon cancer cell lines to change back into normal cells.
Certain fibers appear to be more effective than others in in creasing the levels of SCFAs in the colon. Pectins (from apple, citrus. guar gum, and other
legume fibers) and vegetable-fiber isolates produce more SCFAs than wheat fiber, corn fiber, or oat bran. A recent study looking at fiber from fruits and vegetables
found that people consuming more than two-and-a-half servings of fruits and vegetables daily reduced the risk of colon cancer by 65 percent compared with those
who consumed less than one-and-a-half servings daily. Such studies show that even small changes in diet can produce dramatic reductions in colon cancer risk.
For years scientists have believed that evidence overwhelmingly supported the notion that dietary fiber protects against colon cancer Lately, however, researchers
have discovered that a high-fiber diet isn't enough to overpower the negative effects of a diet high in animal products. In fact, the low rate of colon cancer
among black Africans, originally thought to result from a high-fiber diet, now appears more likely to result from a low intake of animal products.
A number of large studies have found an association between meat consumption and colon cancer. In a study of more than 88,000 women, those who had the
highest ratio of red meat ro chicken and fish intake had a colon cancer risk two and a half times that of the group with the lowest ratio." A study of nearly
50,000 men found that those who ate beef, pork, or lamb as a main dish on an almost daily basis had greater than three times the risk of colon cancer compared
with those who are such foods less than once a month.
Heterocyclic amines—compounds produced during high-temperature cooking-have been suspected as the main carcinogens resulting from meat consumption. A high-fiber
diet isn't enough to counteract the damage from these compounds if meat intake remains high. The gut bacteria still have to digest the meat, and they release
cancer-causing chemicals as a result. The story gets even more complicated, because
ne people have a genetic abnormality that affects their ability to me Webolize heterocyclic amines. What happens is that these individuals
ave an imbalance between Phase 1 and Phase Il detoxification reacrions (see page 48 for more information). Such folks are more likely to
develop colon cancer.
Several studies have shown a strong link between colon cancer and intake of simple carbohydrates, such as sugar. Studies in Uruguay, Italy, and the United
States found that a high-sugar diet increases the risk of colon cancer by 50, 60, and 70 percent, respectively. One problem is that people who get many of their
calories from sugar do not eat a lot of other healthy protective foods, such as fruits, vegetables, and green teas. To make matters worse, sugar and the insulin
your body releases to process sugar have both been shown to enhance the growth of a wide variety of cancer cell types.
FISH OIL: NO FISH STORY
Individuals with a high risk of colon cancer or who tend to form polyps may want to consider supplementation with fish oils. In a study
conducted at the Cancer Research Institute of Harvard Medical School, fish oil supplementation prevented overgrowth of colon cells (hyperproliferation) and polyps
in people who had a prior bout with colon cancer or who formed precancerous polyps.
The subjects were given capsules containing either fish oil or a placebo. Blood samples measuring the fatty acid profile and colon biopsy were performed at the
start of the study and at 3 and 6 months. In addition, colon cells were also analyzed to determine their replication rate.
Before supplementation began, there were no significant differences between the two groups in the rates at which the cells replicated and in the ratio of omega-6
to omega-3 fatty acids (see page 40 for definition and food sources). The researchers discovered that patients whose colon cells showed rapid proliferation had a
higher ratio of omega-6 to omega-3 fatty acids. The rate of hyperproliferation slowed in subjects who took fish oil (a source of omega-3 fatty acids) and who
showed beneficial changes in the omega-6 to omega-3 ratio. In fact, in no subject in the fish oil group had a polyp grow during the yearlong study.
Evidence is mounting that aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) may prevent colorectal cancer 64
These drugs work by slowing down the activity of an enzyme called cyclo oxygenase 2 (cox-2). Cox-2 produces prostaglandins (see page 40) that cause inflammation.
These prostaglandins can also irritate colon cells which causes them to grow. Prostaglandins also may be involved in changing a harmless colon polyp into a
potentially life-threatening tumor.
There's a way you can curb cox-2 without having to take NSAIDs. We recommend that you take advantage of the natural cox-2 inhibitors found in two common spices,
ginger and turmeric, and in green tea.
In animal studies, curcumin has been shown to inhibit all stages of colon cancer--from initiation to promotion and progression--more effectively than aspirin.
Curcumin protects against the disease before,during, and after exposure to carcinogens.
In addition to inhibiting prostaglandin formation, curcumin also exhibits potent antioxidant effects in some experimental studies it was found to be up to 300
times more potent than vitamin E). Curcumin is one of the key natural cancer fighters discussed in Chapter 8.
In high-risk individuals, we recommend taking supplements containing curcumin, the yellow pigment of turmeric, at a dosage of 200 to 400 mg daily. It is also
important to increase your intake of foods containing curry powder and ginger. And it is recommended that you trade your regular beverage for three or more cups
of green tea or ginger tea a day.
According to the Nurses' Health Study, taking multivitamin supplements for 15 years or more has been shown to decrease
colon cancer by up to 75 percent, particularly if folate is among the nutrients ingested. The study focused on nearly 90,000 cancer-free women who from 1980 to
1994 regularly answered detailed questions about their diets, including the use of multivitamins.
Results showed that the reduction in colon cancer risk was stronger for women (ages 55 to 69) who took supplemental forms of folate than for women who
got their folate through diet alone. The reason may be that the form of folate found in vitamins is actually more easily absorbed and utilized than the form supplied by food, even by high-folate foods such as green leafy vegetables like kale, spinach, beet greens, and chard. When
intake of vitamins A, C, D, and E and calcium was also controlled for, results were similar. Long-term use appears to be required to achieve significant protection,
however. After four years, women who used multivitamins containing folic acid had no benefit with respect to colon cancer; there were insignificant risk reductions
up to the fourteenth year. But after fifteen years of use, the results were quite significant.
CALCIUM, VITAMIN D, AND ANTIOXIDANT SUPPLEMENTS TO PREVENT POLYPS
Calcium is thought to offer protection against colon cancer by reducing the concentration of bile
acids that tend to stimulate cellular proliferation. Clinical studies have shown that calcium supplements moderately reduce the risk of recurring polyp growth in
the colon and appear to reduce the risk of colon cancer. In a study published in the New England Journal of Medicine, researchers reported that people who were
prone to polyp formation and who took 1200 mg of calcium daily had a 24 percent decrease in the number of polyps and a 19 percent decrease in the risk of recurrence.
Another study found that use of calcium supplements by cancer patients increased survival times. Such information suggests that calcium may be of value for more than
Colon cancer rates are higher in areas of the United States that get less sunshine. That's significant, because sunshine converts chemicals in your skin into vitamin
D, which your body needs to metabolize calcium. Taking vitamin D supplements along with calcium may provide added protection. Population studies have shown that
higher levels of vitamin D may reduce the risk of colon cancer by approximately 60 percent.
Some studies also suggest that antioxidant supplements may have a small effect in preventing against polyp formation (as well as new colon cancers).Therefore,
supplementing the diet with a multivitamin and mineral formula with sufficient levels of antioxidants, along with some extra calcium (total daily supplement
intake of 1000 to 1500 mg), is a reasonable part of an overall strategy for protection against colon cancer, especially in individuals at high risk.
We've highlighted extra steps you can take to protect yourself against the four main types of cancer. Such measures may be of value if you are particularly
at risk for these diseases, because of family history, genetics, or other risk factors. Many of the steps we've described adequate exercise, a healthy diet,
sensible use of supplements, avoiding known carcinogenic substances or behaviors-apply across the board as components of a complete program for protection against
all forms of cancer and other chronic diseases. In fact, they're pretty good guidelines for good health.
To help you with adding the specific measures recommended in this chapter to your daily routine, we have included them in the guidelines given in Appendix A.
Daily Plan for Preventing Cancer.