Other types of colorectal cancer
Other types of rare colorectal cancers combined account for less than 5 percent of all cases and include:
- Primary colorectal lymphomas: A type of non-Hodgkin lymphoma (NHL), this cancer type develops in the lymphatic system, specifically in cells called lymphocytes. Lymphocytes are a type of white blood cell that helps the body fight infections. NHL may 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. This colorectal cancer type 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 forms 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 develop in the stomach. While most other GISTs form in the small intestine, the rectum is the third most common location. GISTs are classified as sarcomas, or 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, leiomyosarcoma essentially means “cancer of smooth muscle.” The colon and rectum have three layers of the type of muscle affected by leiomyosarcoma, and all three 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 cancer, melanomas may occur anywhere, including the colon or rectum.
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.