Breast Cancer

Definition

Breast cancer is a leading cause of death in developing countries and second leading cause of death in women in developed countries after lung cancer. Both men and women can be diagnosed with breast cancer, but it is more prevalent in women. Clinical breast cancer forms when cells in breast tissues become malignant and grow uncontrollably. The same breast cancer cells can leave the primary site and metastasize (see “Metastasis”) in other parts of body. There are several types of breast cancer, but the most common type is ductal carcinoma in situ, which originates in the lining of the ducts and is confined within the breast duct(s). When ductal carcinoma spreads into surrounding tissues, it is called invasive ductal carcinoma. Invasive ductal carcinoma accounts for 80% of invasive breast cancer. About 10% of invasive carcinomas are invasive lobular carcinomas which begin in the milk-producing glands (lobules) and spread into surrounding tissues. Other rare types of invasive...