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How to Lower Your Cancer Risk

The newspapers and other media are rife with reports that this or that food or chemical or environmental factor—everything from canaries to toasters—causes cancer. But most reports are given out of context, and it's easy to lose sight of the big picture and of the scientific progress that's been made in understanding and preventing cancer.

Cancer does not kill as many people as heart disease, but it still claims 560,000 American lives a year. Four major cancers (lung, colorectal, breast, and prostate) account for slightly more than half of these deaths. Some kinds of cancer (stomach, cervical, and uterine) have dramatically declined in this country, both in incidence and as a cause of death, while others are rising, or seem to be rising. For example, breast and prostate cancer may be occurring more often, or may simply be accurately diagnosed more frequently. (In fact, the number of new cases of prostate cancer has begun to drop, at least for white Americans.) Some other cancers appear to be occurring more frequently because the population is aging.

People often wonder when the "cancer breakthrough" will occur: when will researchers unlock the secret and find the cure? The dramatic breakthroughs we all yearn for—a cancer vaccine, perhaps, or a miraculous cure for all kinds of cancer—may or may not materialize. But enormous progress has been made, and insight into the origins and causes of cancer is growing.

Many of us worry too much about possible cancer promoters that are actually negligible. And at the same time, we may pay too little attention to simple but effective measures we can take to protect ourselves. Important measures for preventing cancer are already at hand.

How does cancer occur?

Genetics has something to do with cancer, though the picture is far from clear. Genes control every aspect of our body chemistry and the growth of cells; some genes may promote cancer, others may protect against it. There is a puzzling interplay of environmental, life-style, and genetic factors, and it's still uncertain where environmental and life-style influences actually come in. Generating energy, which is the basic process of all life, produces unstable molecules known as free radicals that can damage genetic material. This is a normal, everyday process, and most damage is immediately repaired. But sometimes the repair process fails. Exposure to our own hormones, to infectious organisms that have penetrated our immune defenses, and to environmental toxins can also create free radicals that scramble genetic codes and eventually damage cells. If cells are damaged, cell growth may produce tumors rather than copies of healthy cells. It's estimated that three-quarters of all cancers occur largely because of external influences, not our genes.

What you can do

1 Don't smoke. Tobacco use causes more cancer here and in the rest of the world than anything else. The longer you smoke, and the more you smoke, the likelier it is to be lethal. Besides lung cancer, smoking increases the risk of cancer of the bladder, cervix, mouth, throat, pancreas, kidney, and stomach. It may also promote colon and even breast cancer. About 3 million people die of smoking-related causes every year around the world, and that number will rise to 10 million in the next century if the number of smokers continues to increase. Passive smoking (inhaling other people's smoke) causes thousands of deaths a year.

If all tobacco users in this country quit, total deaths from cancer would eventually drop by at least one-third. Lung cancer would become a rare disease, rather than the major cancer killer of both American men and women that it now is.

2 Eat more fruits, vegetables, and whole grains. Diet causes about one-third of all cancer cases, almost as many as tobacco use. Having a diet that consists predominantly of fruits, vegetables, and grains (the current recommendation is at least five servings of fruits and vegetables a day) is the most important factor currently identified in the prevention of cancer through diet. The evidence for this is overwhelming: study after study has confirmed that people who have the highest intakes of fruit and vegetables have the lowest rates of most cancers. Fruits and vegetables contain large amounts of antioxidant vitamins (C and E), as well as folacin, carotenoids, and dietary fiber, which are all important in preventing cancer. Many phytochemicals (plant chemicals) have been shown to have cancer-fighting potential in laboratory studies—and many are still waiting to be discovered.

3 Eat less animal fat. A diet high in animal fat, especially from red meat, has shown up in several studies as a risk factor for prostate and colon cancer. A high-fat diet is also suspected of being a factor in breast cancer, although recent research suggests there is no link. Countries with high-fat diets do have the highest rates of breast and prostate cancer, but other factors could be at work.

4 Don't cook meats at very high temperatures, especially over an open flame. This creates compounds known to promote certain cancers—for example, polycyclic aromatic hydrocarbons (PAHs), which form when meats are charcoal-broiled. An occasional barbecue is probably not harmful. You're better off to steam, braise, bake, poach, stew, or microwave than to barbecue.

5 Limit you alcohol intake. Moderate alcohol intake can help prevent heart disease. ("Moderate" means no more than one drink daily for women, two for men.) But too much alcohol can cause cirrhosis of the liver and liver cancer. Especially when combined with smoking, heavy drinking also contributes to cancers of the mouth, throat, and esophagus, for example. Thus, some experts still say that drinking no alcohol is best.

6 Be active. In the past ten years, studies have suggested that exercise helps prevent breast and prostate cancer, and there's solid evidence it can prevent colon cancer. It's hard to say what level of activity is needed; but moderate activity starting early in a woman's life seems to protect against breast cancer.

7 Control your weight. Being significantly overweight puts you at risk for such diseases as stroke and heart disease, and probably also for some cancers (uterine and postmenopausal breast cancer in women; colon and prostate cancer in men). No one is sure why obesity might boost the risk of cancer. Nevertheless, this is still another reason to maintain a healthy weight.

8 Limit your exposure to the sun. Use a potent sunscreen when you are in the sun. Cumulative sun exposure is responsible for most skin cancers, which account for about 2% of cancer deaths.

9 Limit workplace exposure to chemicals. For people who work with cancer-causing chemicals, such as asbestos, benzene, and formaldehyde, this is a serious problem. However, extensive exposure to such chemicals is uncommon among the population at large.

What about pesticides?

Food is a complex mixture of natural ingredients, not all of them benign. Plants themselves produce pesticides to ward off attack from animals and microorganisms. Our bodies are equipped to defend themselves against most of the potentially harmful elements in foods, just as we have chemical defenses against other kinds of low-level toxins. But it's man-made pesticides that cause the most worry. Humans have been consuming natural pesticides for thousands of years, and we may have ways of protecting ourselves from them, whereas we might be less able to fend off synthetic chemicals. Much remains to be learned about pesticide residues in foods. As yet, there's no evidence that they are a significant cause of cancer.