Cancer is a disease in which abnormal cells grow, divide, and spread. In most cancers, these abnormal cells form a mass called a tumor. (Not all tumors are cancer.) Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. But cancers can spread. They can invade nearby tissues and organs. Or, they can break away and spread to other parts of the body. Symptoms and treatment depend on the cancer type and how advanced it is.
Read more about common types of cancer that affect women.
Learn about all types of cancer at the National Cancer Institute.
Content last updated: June 05, 2014.