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There are several types of colon cancer, and each originates in a different type of cell. A pathologist can determine the type of colon cancer a patient has by looking at a tissue sample under a microscope; this information can then be given to the patient’s oncologists, who can use the cellular classification to determine the most appropriate forms of treatment.

The main types of colon cancer

The most common type of colon cancer is adenocarcinoma (a type of carcinoid tumor mentioned below), but there are several other types, as well. The type of cancer sometimes influences treatment. The main types of colon cancer include:

  • Gastrointestinal carcinoid tumors – These develop in the neuroendocrine cells that form the lining of the gastrointestinal tract. The tumors are relatively slow-growing, although many patients develop several at the same time. The most common type is adenocarcinoma, which forms in the mucus-secreting glands and accounts for the majority of all colon cancer diagnoses.
  • Gastrointestinal stromal tumors – These develop in the interstitial cells of Cajal, which are part of the autonomic nervous system and serve as “pacemakers” for the muscles in the intestine. However, these tumors, which are often referred to as GISTs, are not always cancerous; many are benign (noncancerous) and incapable of spreading.
  • Primary colorectal lymphomas – These develop in the lymphocytes, or immune system cells. Lymphomas of the colon are relatively rare and account for only a small fraction of all colon cancers.
  • Squamous cell carcinomas – These develop in the blood vessels or smooth muscle cells of the colon. There are several different carcinoma subtypes, including leiomyosarcomas and angiosarcomas. These cancers are among the least frequently diagnosed of all colon cancers.

Most of these cancers can also develop in the rectum or other parts of the gastrointestinal tract. For example, a GIST can form in the interstitial cells of Cajal in the stomach or duodenum, rather than in the colon. However, in these cases, the tumors are not considered to be colon cancers, even though they may be referred to collectively as “colorectal cancers.”

Sometimes, cancer can metastasize (spread) to the colon from another part of the body. This is not considered to be a true colon cancer; instead, it remains classified by the part of the body in which it first developed. For instance, rectal cancer that spreads to the colon is diagnosed as metastatic rectal cancer, not colon cancer. 

Moffitt Cancer Center’s expert oncologists can help you learn more about the different types of colon cancer and provide you with detailed information that is specific to your precise diagnosis. There’s no need to request a referral to schedule an appointment; call 1-888-663-3488 or submit a new patient registration form online.