Women in the United States, the United Kingdom and Australia are diagnosed with breast cancer more often than any other cancer. Though it is rare, some men also get breast cancer. Breast cancer grows in the ducts, lobules or tissues of the breast. If left untreated, the cancer may spread, or metastasize, throughout the body causing severe health problems and eventually death. Breast cancer can be treated with surgery, chemotherapy or mastectomy.
Cancer starts when cells in the breast suffer damage to their DNA. Damage can be caused by environmental stressors, mistakes during cell reproduction or, rarely, genetic disorders. The damaged cells reproduce forming a hard lump in the breast known as a tumor. Cancerous tumors are known as malignant tumors. Not all tumors are malignant tumors. Benign tumors can form out of scar-like tissue or cysts in the breast. These may be painful, but they cannot spread the way cancerous tumors do.
Most breast cancers begin growing in the ducts. Ducts are the tubes that carry milk to the nipples. Sometimes cancer may start in the lobules, the milk producing glands in the breast. Rarely, cancer starts in the stoma, the fatty and connective tissue that surrounds the lobules and ducts.
Breast cancer can be treated either locally or systemically. Local treatments are focused to affect only the cancer site. These include radiation therapy and surgery. Surgery may be used to remove a tumor, or in cases where the cancer is advanced, to remove the entire breast. Removal of one or both breasts is known as a mastectomy.
Systemic treatments are designed to treat cancer wherever it is in the body. This is useful if doctors suspect that the cancer has spread from the breast to other parts of the body. Examples of systemic treatments include medication given by mouth or injected directly into the blood stream.