The first sign of breast cancer is usually a lump or a spot seen on a mammogram. Like all cancers, the disease is the result of unrestrained multiplication of cells.
Normal cells divide in a planned way, creating more cells only when needed.
Cancerous cells grow and divide without control or order, often making excess tissue that becomes a tumor. Cancer cells may grow into nearby healthy tissue, or they may break away from the tumor and travel through the blood stream or lymphatic system to other parts of the body. For this reason, breast cancer often spreads into the lymph nodes in the armpit, chest, and collarbone area. Causes There is no known cause, but certain factors increase the odds of the disease. She did not become pregnant before age 30.