There are several types of colorectal cancer, most of which begin as a mass of excess cells (polyp) in the lining of the gastrointestinal tract. While many polyps are benign, some undergo changes and become cancerous (adenoma). If cancer develops, it is broadly classified based on where the first adenoma appeared. If the cancer begins in the colon (the first four feet of the large intestine), it is called colon cancer. If the initial adenoma develops in the rectum (the last several inches of the large intestine leading to the anus), it is referred to as rectal cancer. In either case, the cancer usually starts in the innermost layer of the organ and can potentially grow outward into the blood vessels or lymph nodes.
Cancers of the colon and rectum are further classified based on the type of cell in which the malignancy originates. The specific types of colorectal cancer, which include both colon and rectal cancers, include:
- Adenocarcinoma – Develops in the cells of the mucus-producing glands that lubricate the large intestine (most common)
- Gastrointestinal carcinoid tumor – Starts in the specialized hormone-producing cells in the large intestine
- Gastrointestinal stromal tumor (GIST) – Forms in the interstitial cells of Cajal in the digestive tract
- Primary colorectal lymphoma – Forms in the colon or rectum (this cancer of the immune system most often originates in the lymph nodes)
- Sarcoma – Develops in the blood vessels, muscles or connective tissue in the walls of the colon or rectum (relatively rare)
At Moffitt Cancer Center, the tumor board of specialists in our Gastrointestinal Oncology Program works closely with each patient to reach an accurate diagnosis and develop an individualized treatment plan based on multiple expert opinions. As a large cancer center, we have a level of expertise that far exceeds that of most other providers, especially with regard to rare types of colorectal cancer. Additionally, through our robust clinical trial program, our patients have access to the latest and most innovative treatment options available, and we continue to improve the standard of care for all present and future cancer patients. In recognition of our dedicated efforts and extraordinary results, we have received the prestigious designation of Comprehensive Cancer Center from the National Cancer Institute.