Breast Cancer

Breast cancer is a type of cancer originating from breast tissue; most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas, while those originating from lobules are known as lobular carcinomas. Breast cancer occurs in humans and other mammals. While the overwhelming majority of human cases occur in women, male breast cancer can also occur.

The size, stage, rate of growth, and other characteristics of a breast cancer determine the kinds of treatment; as is the prognosis and survival rates. Treatment may include surgery, drugs (hormonal therapy and chemotherapy), radiation and/or immunotherapy. Surgical removal of the tumor provides the single largest benefit, with surgery alone curing many cases. To increase the likelihood of cure, several chemotherapy regimens are commonly given in addition to surgery. Radiation is used after breast-conserving surgery and substantially improves local relapse rates and in many circumstances also overall survival. Some breast cancers are sensitive to hormones such as estrogen and/or progesterone, which makes it possible to treat them by blocking the effects of these hormones.

Worldwide, breast cancer comprises 22.9% of all cancers (excluding non-melanoma skin cancers) in women. In 2008, breast cancer caused 458,503 deaths worldwide (13.7% of cancer deaths in women). Breast cancer is more than 100 times more common in women than in men, although men tend to have poorer outcomes due to delays in diagnosis.