Breast cancer affects men and women, though it occurs in women much more often. According to the National Cancer Institute, approximately 1 percent of all breast cancers occur in men, who are mostly in their 60s and 70s. According to the Mayo Clinic, breast cancer is more rare in men because they generally have much less breast tissue than women. There are several types of breast cancer that occur in men.
Ductal Carcinoma
This type of cancer, according to the National Cancer Institute, involves cancer developing from the cells lining the ducts of the breast. One form of this disease is infiltrating ductal carcinoma, which is the most common form of this disease. According to the American Cancer Society, this type of breast cancer is diagnosed in 8 out of every 10 cases of male breast cancer. "Infiltrating" refers to the fact that the cancerous cells have spread beyond the duct and into the neighboring tissues within the breast. The other type of ductal carcinoma in which the cancerous cells have not infiltrated the surrounding breast tissue, called ductal carcinoma in situ, is less common.
Paget Disease of the Nipple
The National Cancer Institute reports that Paget disease of the nipple is a form of breast cancer in which cancer begins in the cells of the ducts, but then spreads to the surface of the nipple. According to the Mayo Clinic, the cancer in the nipple causes the skin around the nipple to become scaly and crusty. The American Cancer Society adds that the nipple may become red and itchy, and there may be bleeding or a discharge.
Lobular Carcinoma
In women, lobules produce milk for breastfeeding. Men also have lobules, though they have many less than women. Furthermore, male lobules do not produce milk. Lobular carcinoma, described by both the National Cancer Institute and the American Cancer Society, is cancer that begins in the cells of the lobule. There are two types of lobular carcinoma: "infiltrating" and "in situ." Infiltrating lobular carcinoma is distinct from lobular carcinoma in situ in that the cancerous cells have invaded (or "infiltrated") the breast tissue surrounding the lobule. The American Cancer Society reports that both infiltrating and in situ forms of this cancer are quite rare in men; however, while the National Cancer Institute confirms the rare occurrence of the infiltrating form, they report that lobular carcinoma in situ "...has not been seen in men."
