Magazine article The Saturday Evening Post

The Breast Cancer-Diet Connection

Magazine article The Saturday Evening Post

The Breast Cancer-Diet Connection

Article excerpt


Willy you develop breast cancer? The bad news, according to the latest statistics, is that one in ten women in the United States will. What's more, the number of breast cancer cases in women over age 44 has been steadily increasing since 1960, by almost 2 percent a year.

The reasons for this increase are unclear. We know that cancer of the breast, like other cancers, is a disease of the body's cells. Abnormal, hyperactive growth occurs when cell division is not orderly. This growth results in a buildup of tumors. Despite extensive studies, there is no clear explanation of why and when breast cancers will develop. Probably a combination of heredity and environment is responsible.

A woman's breasts change throughout her life. Such factors as age, menstrual cycle, pregnancy, breast-feeding, and menopause can cause these changes, all of which have been cited as risk factors in breast cancer, but to these another factor must also be added: the role of diet.

Some evidence suggests that a rich diet high in calories promotes rapid growth during childhood leading to early menarche, which is associated with high rates of breast cancer. American women begin menstruation three to six years earlier than Chinese women, who have a lower rate of breast cancer. An energy-rich diet later in life contributes to obesity, which after menopause enhances the growth of breast cancer.

Animal studies in the 1940s first showed a relationship between dietary fat and cancer. rats fed a high-fat diet and exposed to a carcinogen developed more mammary tumors than a control group developed.

In human populations, scientists noted a much lower rate of breast cancer among Japanese and Chinese women, whose diets were much lower in fat than the diets of Western women. They also found that immigrants tothe U.S. from countries with low breast cancer rates generally "adapt" to our higher rates.

According to Dr. Ross Prentice, an epidemiologist at the Fred Hutchinson Research Center in Seattle, the incidence of breast cancer among women from Poland rose after they migrated to the United States. Dr. Prentice has collected information from 21 countries about breast cancer rates for women 45 to 69 years old and has gathered national data on fat calories consumed per capita. He found that the breast cancer rates among women who have migrated from Japan and China to the United States also increased, but more slowly.

The method by which fat appears to increase breast cancer is not yet understood, and the mystery intrigues researchers. Dr. Geoffrey Howe of the Epidemiology Unit of the National Cancer Institute of Canada and colleagues analyzed the original data to evaluate the consistency of 12 case-control studies of diet and breast cancer. Their analysis showed "a positive association between breast cancer risk and saturated fat intake in postmenopausal women." It also showed "a consistent protective effect for a number of markers of fruit and vegetable intake." Vitamin C had the most consistent and statistically significant inverse association with breast cancer risk. Vitamin A may also diminish breast cancer risk.

The researchers concluded: "If these dietary associations represent causality, the attributable risk [i.e., the percentage of breast cancers that might be prevented by dietary modification] in the North American population is estimated to be 24 percent for postmenopausal women and 16 percent for premenopausal women."

In a recent study in northwestern Italy, Dr. Paolo Toniolo of the Department of Environmental Medicine, New York University Medical Center, compared the diets of 250 breast cancer patients against those of 499 healthy women of the same ages. They found a reduced risk for breast cancer "for women who derived less than 28 percent of calories from fat versus more than 36 percent." They found a similarly reduced risk for women who derived less than 9. …

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