Colon polyps

What polyps are

A polyp is a small growth of tissue in the lining of the large bowel (colon) or rectum. Polyps are very common, especially after age 50, and become more frequent with age. Most are benign, but some types are precancerous: over years, often more than a decade, they can turn into colorectal cancer.

This slow development is why so much colon cancer can be prevented: when a polyp is found and removed before it transforms, the cancer does not develop. This is exactly the aim of screening: to find and remove the polyp before it becomes a problem.

Types of polyps

• Adenomas are the most important precancerous type. The risk rises with size, number and the degree of dysplasia (cell change) on biopsy.
• Serrated lesions: some of them, such as sessile serrated lesions, also have precancerous potential, especially when large or in the right side of the colon.
• Small hyperplastic polyps in the rectum are usually very low risk.
• Inflammatory polyps are usually not precancerous, but may accompany inflammatory bowel disease.

A family history of colorectal cancer or advanced polyps and some inherited syndromes (for example familial adenomatous polyposis, Lynch syndrome) raise the risk considerably and call for earlier and more frequent screening.

Symptoms

Most polyps cause no symptoms, which is why screening matters: waiting for symptoms often means being late. Some polyps may bleed and cause visible or invisible blood in the stool, or anemia from slow blood loss; more rarely they cause changes in bowel habit. Polyps usually do not cause abdominal pain.

Blood in the stool, unexplained anemia or a new change in bowel habit should always be assessed, even when the source is thought to be hemorrhoids.

How they are found

• Colonoscopy is the main method, because it allows both detection and removal of polyps in the same session (see colonoscopy).
• Stool tests (for example FIT for occult blood) are used for screening; a positive test is always followed by colonoscopy.
• CT colonography is an alternative in selected cases (a service that may be recommended to you at another center).

A digital rectal examination does not check the whole colon and does not replace screening. In many guidelines screening begins around age 45–50 for people at average risk, and earlier when there is a family history; your doctor will advise on the right time.

Removal of polyps (polypectomy)

Most polyps are removed during colonoscopy with small instruments (forceps or an electrical snare). Removal usually does not feel painful, because the lining of the bowel has no pain receptors. Large or complex polyps may need advanced endoscopic techniques (endoscopic mucosal resection) or, rarely, surgery.

The removed polyp is sent for histopathologic examination, which shows its type, the degree of dysplasia and whether it was removed completely. This result determines when the next colonoscopy is due.

Risks are rare: bleeding (immediately or up to several days later), perforation and complications of sedation. For this reason, after removal, and especially with large polyps, the doctor gives instructions for the following days (activity, diet, medicines that affect clotting). Anticoagulants and antiplatelet drugs are not stopped by yourself for colonoscopy; the plan is decided with the doctor who prescribes them, weighing the risk of bleeding against the risk of thrombosis.

Follow-up after removal

The interval until the next colonoscopy depends on the number, size and type of polyps, on complete removal and on the quality of bowel preparation. It can be anywhere from 1 to 10 years: after one or two small polyps it is usually longer; after many polyps, large polyps or high-grade dysplasia it is shorter. Your doctor sets it based on the histology result, following international guidelines for surveillance after polypectomy.

It is important not to skip the scheduled colonoscopy: people with previous polyps have a higher risk of developing new ones.

Prevention

Regular physical activity, a healthy weight, a diet rich in fiber, vegetables, fruit and whole grains and low in red and processed meat, quitting smoking and limiting alcohol lower the risk of polyps and colorectal cancer. These measures support, but do not replace, screening and follow-up by colonoscopy.

Contact your doctor if you have blood in the stool, anemia, unexplained weight loss or a new and persistent change in bowel habit, or if you are due for screening.