Breast cancer forms in the tissues of the breast, usually the ducts (tubes that carry milk to the nipple) and lobules (glands that make milk). It occurs in both men and women, although male breast cancer is rare.
The most common type of breast cancer is ductal carcinoma, which begins in the cells of the ducts. Cancer that begins in the lobes or lobules is called lobular carcinoma and is more often found in both breasts than are other types of breast cancer. Inflammatory breast cancer is an uncommon type of breast cancer in which the breast is warm, red and swollen.
Some of the risk factors for developing breast cancer include menstruating at an early age, never having given birth or giving birth at an older age, a family history of breast cancer, taking hormones like estrogen for symptoms of menopause, obesity, a lack of exercise, being white and drinking alcohol.