The vast majority of colon cancers are adenocarcinomas. These are cancers of the cells that line the inside surface of the colon. Rarer tumor types include:
- carcinoid tumors, which start in hormone-producing cells in the intestines
- gastrointestinal stromal tumors, a type of soft tissue sarcoma that can be found anywhere in the gastrointestinal tract but is rare in the colon, or other types of sarcoma that start in the blood vessels or connective tissue of the colon
- lymphomas, which are cancers of the immune system that more commonly start in the lymph nodes but can start in the colon
These types may be treated differently than adenocarcinomas. This section on the diagnosis and treatment of colon cancer refers primarily to adenocarcinomas.
About 5 to 10 percent of colorectal cancer cases are hereditary (due to specific mutations in the genes that are passed from parents to children). Our colon cancer experts may offer you genetic testing to see if you have mutations in your genes that can increase your cancer risk. Whether you should have this testing is based on an assessment of your personal risk. Learn more about genetic testing for colon cancer and the types of hereditary conditions that often lead to the disease.