Breast Cancer

Breast cancer starts when cells in the breast begin to grow out of control. These
cells usually form a tumor that can often be seen on an x-ray or felt as a
lump. The tumor is malignant (cancer) if the cells can grow into (invade)
surrounding tissues or spread (metastasize) to distant areas of the body. Breast
cancer occurs almost entirely in women, but men can get breast cancer, too.