Heavy silence: why no one wants to talk about obesity and breast cancer.

• Author: Fumento, Michael

Every October, this country celebrates Breast Cancer Awareness Month. But what are we supposed to be made aware of? That the disease exists? That's hardly necessary. How about that it's the most prevalent female cancer? Most women know that, too. Perhaps women should be made aware of what is probably the single most important controllable risk factor for breast cancer.

No, it's not power lines or DDT or toxic waste dumps. It's obesity.

Federal government weight specialists define obesity for women as having a body mass index of 27.3 or higher. (Your BMI is your weight in kilograms divided by the square of your height in meters.) Many studies have found obesity increases the risk of breast cancer in older women. The National Cancer Institute's 1996 publication "Cancer Rates and Risk" states flatly, "Among postmenopausal women, breast cancer risk increases with weight and body mass."

Obesity greatly raises a woman's risk of getting breast cancer and, because fat obscures the tumor and delays detection, substantially increases the chance that the cancer will be fatal. As a risk factor for breast cancer, obesity is more significant than other risk factors such as an inherited genetic mutation or early puberty. But the connection between obesity and breast cancer is rarely discussed because feminists and fat acceptance activists, aided by sympathetic, intimidated, or clueless journalists, find it ideologically inconvenient.

The evidence is getting harder to ignore. Results from the Boston-based Nurses Health Study, reported last November in The Journal of the American Medical Association, indicate that postmenopausal women who have gained 44 pounds or more since age 18 are twice as likely to get breast cancer as women who have gained less than five pounds. And Harvard University endocrinologist JoAnn Manson, one of the study's lead researchers, says "There seems to be even a stronger association with greater degrees of obesity." Other studies have yielded similar results. The probable explanation, Manson says, is that after menopause fat becomes the primary source of estrogen in a woman's body, swamping outside sources (such as DDT) that environmentalists have tried to link to breast cancer.

A study by researchers at Yale University, reported last September in the American Journal of Epidemiology, found that obese women are more than three times as likely as thin women to have their breast tumors detected at a later, less treatable stage of the...