As demonstrated in this issue of the Townsend Letter, a number of important advances have been made in the treatment of cancer; advances that have the potential to increase survival times, improve quality of life and, in some cases, cure the disease. The stark reality, however, is that a large proportion of people with cancer are still succumbing to it, despite the best that modern medicine has to offer. Consequently, the best strategy available to avoid dying from cancer is not to develop it in the first place.

A considerable body of evidence indicates that many common cancers are caused in large part by environmental and lifestyle factors, and that modification of those factors can significantly reduce the risk of developing cancer. Following is a brief discussion of some relatively simple lifestyle changes that might help prevent cancer.

Avoid excessive sunlight exposure
Being out in the sun too long can increase the risk of melanoma (a form of skin cancer that is often fatal), as well as non-melanoma skin cancers. Light-skinned individuals are particularly susceptible to the adverse effects of ultraviolet rays. On the other hand, sun exposure is needed to stimulate the formation of vitamin D and possibly certain pineal-gland hormones. The amount of sun exposure required to produce adequate amounts of vitamin D varies with skin color, season, latitude, and time of day. Exposure of the face, hands, and arms to one-quarter the amount of sunlight needed to cause a minimal amount of skin redness has been suggested to be the amount needed to maintain adequate vitamin D status. Exposure to the point of suffering sunburn, on the other hand, is clearly too much. Ingestion of nutrients such as lycopene, beta-carotene, vitamin E, vitamin C, and fatty acids from fish oil might help prevent sunburn.

Don't overcook your food
A number of carcinogenic compounds, such as heterocyclic amines and polyaromatic hydrocarbons, are formed when foods are heated to very high temperatures. Of particular concern are charbroiled and fried meat and chicken. The amount of carcinogens ingested can be reduced by cutting away the char that forms during cooking or by reducing cooking temperatures. A grill called "Safe Grill" uses a special filter between the fire and meat to block the formation of both heterocyclic amines and polyaromatic hydrocarbons.

Keep processed-meat intake to a minimum
Processed meats, such as bacon, bologna, salami, sausage, and processed ham, usually contain nitrites, which can be converted in the stomach into nitrosamines. There is good evidence that nitrosamines are an important cause of stomach cancer. The conversion of nitrites to nitrosamines is inhibited by ascorbic acid, so taking vitamin C or drinking orange juice at the same meal as your bacon or your beef jerky might help minimize the damage.

Avoid soft-plastic beverage containers
Many beverages and some foods are packaged in soft-plastic containers. These containers leach compounds into the food or beverage that have estrogenic or antiandrogenic activity, and which may increase the risk of hormone-dependent cancers. Harder plastic containers do not appear to leach these chemicals. Food wrapped in plastic should never be heated in a microwave oven, as doing so greatly increases the migration of chemicals into the food.

Eat lots of fruits, vegetables, whole grains
Numerous epidemiological studies have indicated that eating these foods decreases the risk of developing many different types of cancer. Cruciferous vegetables (e.g., cabbage, Brussels sprouts, broccoli, cauliflower, turnip, rutabaga, kale, collard, radish, and others) appear to be particularly potent anti-cancer foods, but other vegetables and fruits have also demonstrated cancer-fighting activity. Whole grains contain many important micronutrients, as well as fiber. While studies examining the relationship between fiber intake and colon cancer are conflicting, the results are consistent with the possibility of a 10% reduction in risk attributable to the consumption of a high-fiber diet.

Avoid scorching-hot beverages
There is evidence that ingesting very hot drinks increases the risk of developing esophageal cancer, presumably as a consequence of repeatedly burning the esophageal tissues.

Don't smoke
Almost everyone knows by now that smoking is the major cause of lung cancer and also is an important risk factor for oral cancers. Surprisingly, some people who are not willing to quit smoking because of the threat of lung cancer find a way to quit after being told that smoking cigarettes causes wrinkles.

Get regular aerobic exercise
Exercise stimulates the immune system, which plays a key role in preventing cancer. Numerous studies suggest that people can reduce their risk of developing many types of cancer by participating in regular aerobic exercise. In addition, exercise helps prevent or reverse cardiovascular disease, diabetes, hypertension, osteoporosis, depression, anxiety, and fatigue.

Take micronutrient supplements
Research on the relationship between micronutrient intake and cancer has been done mainly in vitro and in animals, although some human research has been published. While more human studies need to be done, the available evidence suggests that B vitamins, vitamin C, vitamin D, zinc, selenium, lycopene, and other nutrients may help prevent cancer. The main caveat with regard to micronutrient supplementation is that beta-carotene supplements have been found to increase the risk of lung cancer among smokers. Consequently, people who smoke should not take beta-carotene supplements.

While following the recommendations in this article will by no means guarantee a lifetime free from cancer, it will almost certainly reduce the risk, perhaps substantially.

Alan R. Gaby, MD

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