The majority of cancer is sporadic or something that happens by chance. Approximately 5 to 10 percent of cancers are caused by gene changes that run in a family. The BRCA genes are just two genes that are known to cause hereditary cancer. There are also genes that increase your risk for other types of cancer, including colon cancer, uterine cancer, and ovarian cancer, and others. If you’re concerned about your personal or family history of cancer, ask your doctor if a genetic risk evaluation may be helpful for you.