The Genetics of Cancer

Cancer is a large group of diseases that result when cells divide out of control and acquire the ability to spread beyond their prescribed borders. Cancer is a genetic disease because it is caused by mutations, but it is rarely inherited because these mutations occur, in most cases, in somatic cells rather than in germ cells. Cancer affects one in three people during their lifetime and is the second leading cause of death in the United States. In women, the most common and most lethal cancers originate in the lung, breast, and colon. In men, cancers of the lung, prostate, and colon predominate. In sharp contrast to cancer, also called a malignant tumor, a benign tumor is defined as a collection of cells that grows out of control but does not spread into surrounding tissues.