A colorectal polyp is a growth on the lining of the colon or rectum.
Polyps of the colon and rectum are most often benign. This means they are not a cancer. You may have one or many polyps. They become more common with age. There are many types of polyps.
Adenomatous polyps are a common type. They are gland-like growths that develop on the mucous membrane that lines the large intestine.
They are also called adenomas and are most often one of the following:
• Tubular polyp, which protrudes out in the lumen (open space) of the colon
• Villous adenoma, which is sometimes flat and spreading, and is more likely to become a cancer
When adenomas become cancerous, they are known as adenocarcinomas. Adenocarcinomas are cancers that originate in glandular tissue cells.
Adenocarcinoma is the most common type of colorectal cancer.
Other types of polyps are:
• Hyperplastic polyps, which rarely, if ever, develop into cancer
• Serrated polyps, which are less common, but may develop into cancer over time
Polyps bigger than 1 centimeter (cm) have a higher cancer risk than polyps smaller than 1 centimeter. Risk factors include:
• Family history of colon cancer or polyps
• A type of polyp called villous adenoma
A small number of people with polyps may also be linked to some inherited disorders, including:
• Familial adenomatous polyposis (FAP)
• Gardner syndrome (a type of FAP)
• Juvenile polyposis (disease that causes many benign growths in the intestine, usually before 20 years old)
• Lynch syndrome (HNPCC, a disease that raises the chance of many types of cancer, including in the intestine)
• Peutz-Jeghers syndrome (disease that causes intestinal polyps, usually in the small intestine and usually benign)