Other types of colorectal cancer
There are many other types of rare colorectal cancers, and combined these types account for just 5 percent of all cases. Below are examples of other colorectal types:
- Gastrointestinal carcinoid tumors: This slow-growing cancer forms in the neuroendocrine cell (a nerve cell that also creates hormones) in the lining of the gastrointestinal tract. These tumors account for just 1 percent of all colorectal cancers, but half of all of the cancers found in the small intestine.
- Primary colorectal lymphomas: A type of non-Hodgkin lymphoma (NHL), lymphomas are cancers that develop in the lymphatic system from cells called lymphocytes. Lymphocytes are a type of white blood cell that helps the body fight infections. NHL can develop in many parts of the body, including the lymph nodes, bone marrow, spleen, thymus and the digestive tract. Primary colorectal lymphomas account for just 0.5 percent of all colorectal cancers, and about 5 percent of all lymphomas. The disease usually occurs later in life, and is more common in men than women.
- Gastrointestinal stromal tumors: Also known as GISTs, this is a rare type of colorectal cancer that starts in a special cell found in the lining of the gastrointestinal (GI) tract called interstitial cells of Cajal (ICCs). More than 50 percent of GISTs start in the stomach. While most of the others start in the small intestine, the rectum is the third most common location. GISTs are classified as sarcomas, cancers that begin in the connective tissues, which include fat, muscle, blood vessels, deep skin tissues, nerves, bones and cartilage.
- Leiomyosarcomas: Another form of sarcoma, leiomyosarcomas essentially means “cancer of smooth muscle.” The colon and rectum have three layers of the type of muscle that can be affected, which all work together to guide waste through the digestive tract. This rare type of colorectal cancer accounts for about 0.1 percent of all colorectal cases.
- Melanomas: Though most commonly associated with the skin, melanomas can occur anywhere, including the colon or rectum.
- Squamous cell carcinomas: Some parts of the GI tract, like the upper part of the esophagus and the end of the anus, are lined with flat cells called squamous cells. These are the same type of cells that are found on the surface of the skin. Cancers starting in these cells are called squamous cell carcinoma.
Treatment options for colorectal cancer
Most often, colorectal cancer is treated with surgery. Other treatments for colorectal cancer include chemotherapy, targeted therapy and radiation therapy.