Breast cancer

Alternative names:

carcinoma of the breast

Definition:

A malignant form of cancer that develops in breast tissue.

Causes, incidence, and risk factors:

The most common type of breast cancer begins in the lining of the ducts and is called ductal carcinoma. Another type, called lobular carcinoma, arises in the lobules. For most types of breast cancer the cause is unknown.

Recently two genes, BRC1 and BRC2 have been implicated in a familial type of breast cancer. A number of other predisposing factors have been identified including obesity, early menarche, and delayed or absent child bearing. Breast cancer may occur in men as well as women, but is much more common in women. Statistics show that one in 8 or 9 American women will develop breast cancer at some point in life, based on full life expectancy.

The risk increases exponentially after age 30. The average age of women diagnosed with breast cancer is 60 years. In general, the rate of breast cancer is lower in underdeveloped countries and higher in more affluent countries (with the exception of Japan where the rate is quite low). In the U.S., whites (especially those of northern European descent) have a higher incidence compared to non-whites. However, the incidence in non-whites, specifically blacks, is increasing, particularly in women under age 60.

Other risk factors include having a family history of breast cancer, particularly in mother or siblings; a past medical history of breast cancer , ovarian cancer, uterine cancer, or colon cancer; early menarche (start of menstruation before age 12) and/or late menopause (after age 55); no pregnancies or a first pregnancy after age 30; and radiation exposure. Post-menopausal estrogen therapy and oral contraceptive use (such as estrogens and progestin oral contraceptives) were considered possible risk factors, but the majority of recent studies do not confirm such risk.

Research suggests that a person's diet may affect the chances of getting some types of cancer. Breast cancer appears to be more likely to develop in women whose diet is very high in fat. Older women who are overweight also seem to have a greater risk. Some scientists believe that a low-fat diet, eating well-balanced meals with plenty of fruits and vegetables, and maintaining ideal weight can lower a woman's risk.

There are also studies that suggest a slightly higher risk of breast cancer among women who drink alcohol. The risk appears to go up with the amout of alcohol consumed., so women who drink should do so in moderation.

The possible link between diet and breast cancer is still under study.