Cancer Control

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Researchers have also begun to look at how lifestyle habits during childhood influence breast-cancer rates. This summer Karin Michels, an epidemiologist at Brigham and Women's Hospital in Boston, released a study in which the mothers of more than 2,000 nurses were asked to recall what their daughters ate as preschoolers. She found that each additional weekly serving of French fries consumed from ages 3 to 5 increased the risk of getting breast cancer as an adult 27%. Oddly enough, the same wasn't true of other high-fat foods, such as ice cream or hamburgers.

Michels is the first to admit that her study alone isn't enough to establish the importance of childhood diet in breast-cancer incidence, but other work seems to support the idea. Dr. Steven Narod, a preventive-medicine geneticist at the University of Toronto, studied a group of Filipino women and found that women whose mothers cooked extensively with coconut oil, high in saturated fat, had higher rates of breast cancer than women whose mothers did not rely so heavily on the oil.

Childhood diet also influences two known risk factors for breast cancer: the timing of a girl's first menstrual period and her height (taller women are at slightly higher risk of developing breast cancer). Last year, in a study of over 117,000 Danish women, researchers concluded that girls who experienced the largest growth spurts from ages 8 to 14, when breast tissue is maturing, had the greatest chance of getting breast cancer later. Narod theorizes that the developing breast cells become particularly sensitized to the effects of growth factors and hormones. "More studies are suggesting that life events around the time of breast development may be critical in impacting risk and prevention of breast cancer," he says.

Meanwhile, other scientists are trying to determine how exercise affects the development of breast cancer. The American Cancer Society recommends that women adopt a fairly intense program if they hope to protect themselves from breast tumors. Its data show that a minimum of an hour and 15 minutes of brisk walking each week can reduce the risk of cancer 18%, while logging 10 hours a week can have an even greater benefit.

What's not clear is whether physical activity helps directly--by influencing levels of estrogen and other body chemicals--or indirectly, by promoting weight loss. "We don't understand all the various potential mechanisms involved," admits Dr. Moshe Shike, director of clinical nutrition at Memorial Sloan-Kettering Cancer Center in New York City, "but taking exercise and diet factors together is helpful in reducing risk."

That may sound vaguer than women might ideally like, but at least it's a start. And it's a lot more honest than the big claims found in popular books touting anticancer diets. No diet and exercise program is ever going to completely eliminate risk, explains Michels, because "no one factor alone causes breast cancer." Eating French fries as a toddler, say, won't doom you, but the wrong childhood diet coupled with a sedentary lifestyle, weight gain and not giving birth could be a formula for disaster. Luckily, as researchers identify more ingredients in the formula, women are gaining more control of their fate. π