RECENT days have been good ones in the war on cancer. No, researchers did not come up with a new treatment. What happened was potentially more important: The nation began to focus more attention on preventing the disease.
The thanks go to Dr. Bob Arnot, whose new best-seller, "The Breast Cancer Prevention Diet," launched a long-overdue (albeit acrimonious) debate about how what we eat affects cancer risk. While critics accuse Dr. Arnot of promising more than science can deliver, the resulting food fight will prove as important a milestone as the tobacco battles of the 1960s.
Some parts of the diet-cancer link remain murky. Others are abundantly clear. Alcohol, for example, increases breast cancer risk. Research studies show that those who take even one drink a day -- if it's every day -- increase their risks by more than 50 percent, compared with non-drinkers. The reason, apparently, is that alcohol interferes with the action of folic acid, a B-vitamin that helps repair damaged DNA that could otherwise turn a normal cell into a cancer cell.
Stock up on veggies
Also clear is the value of vegetarian diets. Numerous studies show that vegetarians generally have about half the cancer risk of meat eaters, after controlling for smoking and other factors. Evidence is particularly strong for colon cancer, where a vegetarian diet cuts the risk by fully two-thirds.
No one knows what part of meat actually promotes cancer, any more than we know what part of tobacco smoke leads to lung cancer. Under suspicion are carcinogens, called heterocyclic amines, that form as meat cooks. And here, the supposedly healthy "white meats" score no points at all; grilled chicken has 15 times the carcinogen load of a typical hamburger. In a study of 32,000 men and women, researchers at California's Loma Linda University found that those eating white meat just once per week had 55-percent higher colon cancer rates than those avoiding meat altogether, and people who had white meat more than once per week had a 300-percent higher risk.
More controversial is the role of fats. The Harvard Nurses' Health Study found no link between fats, in general, and breast cancer risk. On the other hand, New York University researchers, who compared the diets of 250 women with breast cancer to those of 499 women without cancer, gave olive oil a not-guilty verdict, but linked meat, cheese, butter and milk to a substantial increase in risk.
The data are complex, but the lesson is simple: We don't know exactly why smokers have more lung cancer, but we know enough to quit. While researchers have not teased apart all the elements of our diet that encourage cancers to flourish, it's high time we emulated the diets of those who keep this disease at arm's length.
The changes are not so difficult. When we cook spaghetti, we simply favor the light marinara sauce instead of the cheesy Alfredo.
This is not a time for finger-pointing. When research links certain foods to cancer, people with the disease may feel somehow blamed. From my standpoint as a physician, there is no place for blame in cancer research or cancer treatment.
No one could have known in advance what these studies might show.
And few doctors have taken the time to guide their patients in putting nutrition to work. Knowledge should empower us. It should let us make choices that can keep us healthy.
If we focus our attention there, we can go a long way toward protecting ourselves and our families.
Neal D. Barnard, M.D., author of "Eat Right, Live Longer" and "Foods That Fight Pain," founded the Washington, D.C.-based Physicians Committee for Responsible Medicine.
Pub Date: 12/06/98