Breast cancer is an uncontrolled growth of breast cells. Normally, the cells in our bodies replace themselves through an orderly process of cell growth: healthy new cells take over as old ones die out. But over time, some abnormal changes might occur in cells resulting uncontrolled growth. The changed cells gain the ability to keep dividing without control or order, producing more cells just like it and forming a tumor.
Breast cancer refers to cancers originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Treatment includes surgery, drugs (hormonal therapy and chemotherapy), and radiation.
Worldwide, breast cancer comprises 10.4% of all cancer incidence among women, making it the second most common type of non-skin cancer (after lung cancer) and the fifth most common cause of cancer death. In 2004, breast cancer caused 519,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths). Breast cancer is about 100 times more common in women than in men, but survival rates are equal in both sexes.
For self examination techniques and other queries, you should see your physician.