Breast Cancer: A Puzzling Plague

(4 of 6)
Doctors have long been convinced that some people are genetically predisposed to develop breast cancer. A woman whose mother or sister had the disease before menopause has five to six times the usual risk of developing it. If either one had the disease in both breasts, then the woman's risk is five to 10 times the norm.

Though scientists do not know how breast cancer begins, they do have some ideas about how it progresses. The female hormone estrogen, which is produced in the ovaries and causes a young girl's breasts to develop, also plays an unmistakable role in promoting the growth of tumor cells. Why do childlessness, late menopause, early onset of menstruation and delayed childbearing all increase the risk of breast cancer? One likely explanation is that all involve a prolonged, uninterrupted presence of high levels of estrogen in the bloodstream. Doctors have also noticed that women whose ovaries were removed before age 40 rarely get breast cancer.

Researchers focusing on the role of fat in the development of cancer have been particularly intrigued by the estrogen connection. Biologists have long known that estrogen is produced not only in the ovaries but also in fat cells. Obese women have higher levels of estrogen than thin ones -- a probable factor in their greater risk of breast cancer after menopause.

But it has been only in the past five years that researchers have found a link between estrogen levels and fat in the diet. Women who eat lots of hamburgers, thick shakes and other fatty foods have higher overall levels of estrogen and especially large amounts of the "biologically active" form. Equally significant, endocrinologist David Rose of the Naylor Dana Institute in Valhalla, N.Y., has found that when women switch to a very low-fat diet (20% of total calories), their estrogen levels quickly drop by 20%. Advocates of the dietary-fat theory regard this observation as a crucial bit of supporting evidence. Given estrogen's established role in promoting breast cancer, the fact that fatty foods directly affect estrogen levels means that, as Maureen Henderson puts it, "it's biologically rational that fat can influence cancer."

Considering all the fuss over fish oil and polyunsaturates in the world of heart disease, one might wonder if the type of fat consumed makes any difference. "The data are very confusing on this," admits Rose. Some researchers believe that certain fats are more villainous than others with respect to cancer, but Henderson and others say all fat should be reduced. Drastically.

THE MAMMOGRAM MUDDLE

Until the government decides to fund a long-term dietary study and until the work is completed, the value of an ultralow-fat diet in preventing breast cancer will remain open to question. For women 40 or older, however, there is one bit of medical counsel that has almost unanimous approval: Get a mammogram. Now. And do it regularly.

1. Why McCain Picked Palin
2. The Palin Pick: Bold or Disastrous?
3. McCain's Surprise Pick: Sarah Palin
4. Klein: Obama's Speech 'Very Tough'
5. McCain's Prickly TIME Interview
6. GM Recalling 944,000 Vehicles
7. Will Women Vote for Palin?
8. The Web's Word: Obama Is Not the Antichrist
9. Narrowing World Health Disparities
10. Russia 'to Absorb' South Ossetia