Types of Rectal Cancer

Most people who are diagnosed with rectal cancer have a type called adenocarcinoma. There are other rarer tumor types too. These other types of rectal cancer may be treated differently than adenocarcinoma. The section of this guide on the diagnosis and treatment of rectal cancer refers primarily to adenocarcinoma.

Learn more about the types of rectal cancer below.

Adenocarcinoma

The vast majority of rectal cancer is adenocarcinoma. This is a cancer of the cells that line the inside surface of the rectum.

Carcinoid Tumors

Carcinoid tumors start in hormone-producing cells in the intestines.

Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors can be a type of soft tissue sarcoma that can be found anywhere in the gastrointestinal tract but is rare in the rectum. These tumors can also be other types of sarcoma that start in the blood vessels or connective tissue of the colon. 

Lymphoma

Lymphoma is a cancer of the immune system. It more commonly starts in the lymph nodes but can start in the rectum. 

Hereditary Rectal Cancer

About 5 to 10 percent of people get colorectal cancer because of specific mutations in the genes that are passed from parents to children, which are referred to as hereditary. MSK’s experts may offer you genetic testing to see if you have hereditary 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 colorectal cancer and the types of hereditary conditions that often lead to the disease.