What is Male Breast Cancer?

Breast cancer begins in the cells of the breast. Breast cancer may start in the lobules, which are milk-producing glands, or in the ducts, which are tubes that carry milk to the nipple. Occasionally, breast cancer starts in the stroma, the fatty and connective tissues in the breast. Breast cancer may begin as a small tumor in the breast, but may eventually grow and spread to nearby tissue. Once the tumor reaches the blood vessels or lymph nodes, it can spread to other parts of the body. There, it can form new tumors on other tissues or organs.

About 99% of all breast cancer cases occur in women. However, men can also develop breast cancer, since all men have a small amount of breast tissue. In men, breast tissue is made up mainly of ducts, and has very few lobules. Thus, breast cancer in men almost always starts in the ducts. Men may develop the following types of breast cancer:

• Ductal carcinoma in situ (DCIS) - DCIS is a non-invasive cancer in which the cells inside a milk duct have mutated and become cancerous, but have not broken out of the duct or invaded any healthy breast tissue. DCIS makes up about 10% of all breast cancer diagnoses in men and can usually be cured with surgery.
• Invasive ductal carcinoma (IDC) - IDC is cancer that originated in the milk duct but has broken through the duct and invaded healthy breast tissue. IDC is the most common type of breast cancer in men and makes up about 80% of all diagnoses.
• Inflammatory breast cancer - Inflammatory breast cancer (IBC) is a rare but highly aggressive disease. In IBC, cancer cells clog the lymph vessels in the skin, causing a buildup of lymph fluid in the breast. This causes swelling, redness, and a dimpled texture on the affected breast, rather than a mass or lump. IBC is very rare in men.
• Paget's disease - Paget's disease is a rare type of cancer that causes the skin of the nipple and areola to become red, scaly and crusted. Breast cancer that starts in the ducts can spread to the surface of the skin and cause this condition. Men are more likely to develop Paget's disease than women, since male breast cancer develops close to the nipple.