March is National Colorectal Cancer Awareness Month
Types of cancer in the colon and rectum
Adenocarcinomas make up more than 95% of colorectal cancers. These cancers start in cells that make mucus to lubricate the inside of the colon and rectum. When doctors talk about colorectal cancer, they are almost always talking about this type. Some subtypes of adenocarcinoma, such as signet ring and mucinous, may have a worse prognosis (outlook).
Other, less common types of tumors can also start in the colon and rectum. These include:
Carcinoid tumors start from specialized hormone-making cells in the intestine. They are discussed in Gastrointestinal Carcinoid Tumors.
Gastrointestinal stromal tumors (GISTs) start from specialized cells in the wall of the colon called the interstitial cells of Cajal. Some are non-cancerous (benign). These tumors can be found anywhere in the digestive tract, but are not common in the colon. They are discussed in Gastrointestinal Stromal Tumor (GIST).
Lymphomas are cancers of immune system cells that typically start in lymph nodes, but they can also start in the colon, rectum, or other organs. Information on lymphomas of the digestive system is included in Non-Hodgkin Lymphoma.
Sarcomas can start in blood vessels, muscle layers, or other connective tissues in the wall of the colon and rectum. Sarcomas of the colon or rectum are rare. They are discussed in Soft Tissue Sarcoma.