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Sidney Kimmel Cancer Center / Centers & Clinics

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Breast Cancer in Men

Breast Cancer in Men Diagnosis

Fewer than 1% of all breast cancers are in men, but one man in 1000 will develop breast cancer in his lifetime.  Many people are surprised to learn that men have a small amount of breast tissue, milk ducts and estrogen in their bodies. 

Normally, a man’s breast tissue is too small to be seen or felt.  Sometimes, men have an increase in estrogen, causing them to develop more breast tissue, a condition known as gynecomastia.  Gynecomastia is not the same as having breast cancer, though men with gynecomastia do have a slightly higher risk of developing breast cancer. 

Other conditions which may increase the risk of developing breast cancer include Klinefelter’s syndrome (an inherited genetic abnormality), liver or testicular disease, and obesity.  A man who is a carrier of a known gene mutation for breast cancer (BRCA1/BRCA2), particularly the BRCA2 mutation, is also at higher risk for developing breast cancer.  Just as in female breast cancer, however, the cause is often unknown.

Most male breast cancers are invasive ductal carcinoma.  This cancer begins in the milk duct of the breast and can invade nearby tissue, causing a thickening or lump behind the nipple.  It is not unusual for men to delay seeking care for a lump until it has been there for quite some time, it becomes uncomfortable, or they begin to have other symptoms.  For this reason, breast tumors in men are, on average, larger on diagnosis than in women.

Breast Cancer in Men Staging and Treatment

Staging and treatment of male breast cancer are similar to staging and treatment of breast cancer in women.  Treatment includes local therapy and may also include systemic therapy. 

Local therapy is used to prevent the cancer from coming back in the breast. In men, surgery will most often include mastectomy to remove all of the breast tissue, and may also include radiation.

Systemic therapy is used to prevent the disease from coming back or spreading to another part of the body. This may include endocrine (hormone) therapy, chemotherapy, and therapy that targets the HER2 protein.  Most breast tumors in men are sensitive to estrogen and/or progesterone (hormone-receptor positive), making endocrine therapy an important part of the treatment plan.

Your treatment plan will be based on the features of the tumor (type, tumor grade, hormone receptor status, and HER2 status) and the stage of the disease (tumor size and node status). Your oncology team will recommend a treatment plan based on what is known about male breast cancer in general and tailored to what is known about your disease.