Breast Cancer - Causes, Symptoms And Treatment Cancer is a disease which is characterized by the uncontrolled growth of abnormal cells. Breast cancer is any type of malignant growth in the breast tissue. Some women who have a personal or family history indicative of a hereditary cancer syndrome who have not tested positive for a BRCA mutation may still have an elevated risk for these cancers. Almost all breast cancers occur in women and it is also found that it is very few occur in men. About 200,000 women in the United States are diagnosed with breast cancer each year.