My mother died of breast cancer when she was in her late 50s. Is there anything I can do to prevent getting breast cancer? I am particularly concerned as to whether to follow my doctor's advice and start taking estrogen now that menopausal symptoms have started.
A history of breast cancer in another family member does increase your own risk of developing breast cancer. The increased risk, however, would be much greater if your mother, or sisters, developed breast cancer before the age of 40. Nonetheless, the frequency of breast cancer is high enough that you have ample reasons to take all precautions to avoid it.
Unfortunately, researchers have not discovered strong evidence that any measures are effective in preventing breast cancer. Results of one recent study do suggest that four hours or more of aerobic exercise per week reduces the risk of of breast cancer in young women. Diets low in fat, particularly saturated fat, may decrease the risk of breast cancer because the incidence is low in countries where people consume a low-fat diet.
Two other careful recent studies have failed to confirm this idea, however: Neither study was able to show any relationship between the amount of total or saturated fat, or total caloric intake, with the subsequent development of breast cancer. (On the other hand, there is ample evidence that a low-fat diet does protect against coronary heart disease (CAD) and colon cancer.)
About 40 studies have investigated the effects of postmenopausal estrogen replacement on the development of breast cancer.
They conclude that there does seem to be a small increase in the risk of breast cancer in those who have been on estrogen replacement for more than five years. The increased risk is the same for those with or without a family history of breast cancer.
It is important to keep in mind that many studies have clearly shown that estrogen replacement provides significant protection against osteoporosis and CAD; the latter is a far more common cause of death than breast cancer -- or all cancers, for that matter --in postmenopausal women. (In general, hormone replacement includes a progestin as well as estrogen, except in women who have had their uterus removed, because estrogen alone raises the risk of uterine cancer. The addition of progestin eliminates the risk of uterine cancer and has no effect on breast cancer.)
Given the relative lack of effective measures to prevent breast cancer, the best strategy for you and others to follow is to practice breast self-examinations and get regular mammograms
to detect breast cancer at the earliest possible stage.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.