Male Breast Cancer

Male breast cancer is a type of cancer that grows in the breast tissue in your chest. Although men and people assigned male at birth (AMAB) don’t have breasts that produce milk, they have fatty tissue, ducts and breast cells that can become cancerous. Cancer develops when cells in these tissues grow uncontrollably, forming a tumor.

Male breast cancer is extremely rare compared to breast cancer in women and people assigned female at birth (AFAB). Still, many steps involved in diagnosing and treating breast cancer are similar regardless of sex.

Types of male breast cancer

Cancer is most likely to form in your breast ducts. Ducts are tubes that connect glands called lobules to your nipple. Types include:

• Invasive (infiltrating) ductal carcinoma: Up to 90% of male breast cancers are invasive ductal carcinoma, the most common type of breast cancer. Cancer begins in your breast ducts and spreads to other parts of your breast. Cancer cells may also spread to other areas of your body.
• Ductal carcinoma in situ (DCIS): Cancer cells grow in the lining of your breast ducts. “In situ” means that the cells haven’t spread to other parts of your breast or the rest of your body.
• Lobular breast cancer (invasive lobular carcinoma): Cancer cells form in the lobules. Like invasive ductal carcinoma, lobular breast cancer can spread to other parts of your body.

Rarer types of male breast cancer include inflammatory breast cancer and Paget’s disease of the breast.

How common is male breast cancer?

It’s uncommon. Only about 2,800 people AMAB in the United States receive this diagnosis annually. This is less than 1% of total breast cancer cases among either sex.