Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.

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.

A localized swelling, knot, bump, bulge or protuberance in the breast. Breast lumps may appear in both sexes at all ages. ...