Polyps are abnormal growths rising from the lining of the large intestine or colon. Polyps may be flat or sessile or develop on a stalk like broccoli. Polyps are one of the most common conditions affecting the colon, occurring in 15-20 percent of the adult population. Most polyps are asymptomatic and never turn into cancer. However, a small percentage of polyps can slowly grow and develop over 8-10 years into colon cancer. Almost all colon cancers develop from polyps. Colonic polyps are usually not associated with symptoms. When they occur, symptoms include rectal bleeding, bloody stools, mucous discharge, and abdominal pain. A change in bowel habits may occur and include constipation and diarrhea.
Malignant potential of polyps are associated with the presence of dysplasia or pre-cancerous changes, the type of polyp, and the size of the polyp.
- Types of polyps
- Tubular adenoma - 5% risk of cancer
- Tubulo-villous adenoma – 20% risk of cancer
- Villous adenoma – 40% risk of cancer
- Size of polyp
- <1cm - <1% risk of cancer
- 1-2cm – 10% risk of cancer
- >2cm – 15% risk of cancer
How are colonic polyps diagnosed?
Colonoscopy remains the gold standard for diagnosis of colonic polyps. During a colonoscopy, your doctor spends the majority of the examination looking for changes to the normal landscape of the colon lining and removing anything that looks suspicious for a polyp. Other methods of detection include x-ray with a virtual colonoscopy or barium enema.
How are colonic polyps treated?
Since there is no fool-proof way of predicting whether or not a polyp is or will become cancer, all polyps should be removed. Most polyps can be removed simply and safely at the time of your colonoscopy. Colonoscopies can actually prevent cancer from developing by removing the polyps before they become cancerous. Very large polyps may require removal with a new technique called endoscopic mucosal resection (EMR). If a polyp is too large to remove safely endoscopically then surgical resection may be needed.
What is the prognosis of colonic polyps?
People with a history of polyps have an increased risk of developing polyps again over their lifetime and should have regular exams by a physician specially trained to treat diseases of the colon and rectum.