By Sharon Giordano, MD

Question
How common is male breast cancer, and how is it different from female breast cancer?

Answer:
In 2003, approximately 1,300 new cases of male breast cancer will be diagnosed, according to data from the National Cancer Institute cancer registry. This represents around 1% of all cases of breast cancer. The average age of diagnosis of breast cancer in men is five to 10 years older than for women with breast cancer. However, men with breast cancer have similar survival rates as women with breast cancer.

The cause of breast cancer in men is not well understood. Men who have female relatives with breast cancer are at higher risk than the general population, although the overall risk is still low. Other risk factors include a history of testicular abnormalities, infertility, breast trauma, nipple discharge, and a rare genetic condition called Klinefelter’s syndrome.

Approximately 10-20% of men with breast cancer will be carriers of a breast cancer-causing genetic mutation (BRCA2), which can also cause breast and ovarian cancer in women. Men who have this mutation can pass it to their children. Therefore, men with breast cancer should consider genetic testing or counseling.

Breast cancer in men tends to be diagnosed at a more advanced stage than breast cancer in women. Tumors in the male breast are larger, and more men have had cancer spread to the lymph nodes by the time they are diagnosed. Probably, this finding reflects the lack of public awareness about breast cancer in men. Many men are not alert to the possibility that they can develop breast cancer and may ignore warning symptoms. Men who notice a lump under the nipple, nipple discharge, or nipple bleeding should promptly seek the care of a physician for further evaluation.

Breast cancer in men can be confused with a common benign condition called gynecomastia, in which men develop swelling of the breast tissue under the nipple. Mammograms can be used to help differentiate gynecomastia from breast cancer, but any suspicious mass should be biopsied to rule out a diagnosis of cancer.

In general, breast cancer in men is treated similarly to breast cancer in women. The most common surgical therapy is a modified radical mastectomy, which removes the breast tissue and the lymph nodes underneath the arm. Lumpectomy is usually not recommended because of the small amount of breast tissue in men.

Since male breast cancer is a rare disease, limited information is available regarding the use of chemotherapy. Small studies have suggested that chemotherapy will help reduce the risk of breast cancer recurrence. Since women who receive chemotherapy clearly have improved survival, at M. D. Anderson, we recommend chemotherapy for men and use the same guidelines that are used in women. After surgery and chemotherapy, radiation therapy is recommended to men who had large tumors or cancer in many lymph nodes.
The final component of therapy is treatment with a hormone blocker, Nolvadex® (tamoxifen), for men whose tumors are estrogen receptor positive. Interestingly, men are more likely than women to have tumors with estrogen receptors. This may indicate that breast cancers in men are more stimulated to grow by hormones, and more responsive to therapy with hormone-blocking medication.
More than 90% of tumors in men will have the estrogen receptor, and those men will benefit from taking five years of tamoxifen. Although Arimidex® (anastrozole), another hormone blocker, is increasingly used to treat breast cancer in women, it has not been adequately tested in men. Therefore, tamoxifen remains the drug of choice to treat early-stage breast cancer in men.
More research is clearly needed to better understand the causes and to improve the treatment of men with breast cancer. At M. D. Anderson, we are working to set up a program to learn more about breast cancer in men. As we obtain more knowledge about this rare disease, we will continue to make progress in the prevention and treatment of male breast cancer.