What is a polyp in colorectal cancer?

A polyp is a growth inside the colon or rectum. Colorectal cancer often begins as one of these growths, which is why finding and removing polyps can prevent the cancer from ever forming.

Polyps are common. Among adults over 50, roughly 30% have an adenoma, the polyp type most linked to cancer. With high-definition scopes it can be as high as 50%. Having one is close to ordinary. It is not a diagnosis of cancer, and not every polyp becomes cancer.

Not all polyps are the same

Your pathology report will name the type. Adenomas are one family. Serrated polyps are another, and that group includes hyperplastic polyps, sessile serrated adenomas, traditional serrated adenomas, and mixed serrated polyps. The NCI is candid that the clinical meaning of serrated lesions is still uncertain, because the natural history of any polyp is hard to study.

Size and features matter more than the count. Doctors use the term advanced neoplasia for an adenoma 10 mm or larger, a villous adenoma, an adenoma with high-grade dysplasia, or one that already contains invasive cancer. In one large screening study, 10.5% of people had advanced neoplasia.

Why colonoscopy is different from the other tests

A colonoscopy can find a polyp and take it out. Stool tests and CT colonography cannot.

Most expert groups say people at average risk should start screening at age 45 and continue through age 75. For ages 76 to 85, the decision depends on your health and past screening results.

Expert groups suggest schedules like these for average-risk adults:

• Stool blood test or FIT, every year or two.
• Stool DNA-FIT, at least every 3 years.
• CT colonography, every 5 years.
• Flexible sigmoidoscopy, every 5 or 10 years.
• Colonoscopy, every 10 years.

There is one condition attached to all of them. An abnormal result from a stool test, CT colonography, or flexible sigmoidoscopy should be followed by a colonoscopy. Without that step, the screening may not help.

What to do after a polyp is found

Ask three questions before you leave, and write down the answers. How many polyps were removed? What type and size were they? When is my next colonoscopy due?

That last answer is not a standard 10 years for everyone. The interval is set by what the pathologist found, and it can be much shorter. Put the date in your calendar the day you get it, because the gap is measured in years and is easy to lose track of.

If a stool-based test came back abnormal, book the colonoscopy now rather than repeating the stool test. And tell your doctor if close relatives have had colorectal cancer or advanced polyps, since that may mean starting earlier and screening more often.