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 far more common than most people expect. Among adults over 50, roughly 30% have an adenoma, the polyp type most linked to cancer. With today's high-definition scopes the figure reaches 50%. Having one is close to ordinary. It is not a diagnosis of cancer, and most polyps never become 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.

What removing them accomplishes

The National Polyp Study suggested that removing polyps cut later colorectal cancer cases by 76% to 90%. A follow-up study suggested roughly a 53% drop in deaths from colorectal cancer. The NCI notes both findings may be biased and should be read with caution, but the direction is not in doubt.

The size point is practical. Most of the benefit likely comes from removing large polyps, meaning those over 1.0 cm. Whether removing the small ones helps is genuinely unknown, and small ones are far more common.

Why colonoscopy is different from the other tests

A colonoscopy is the only screening test that can find a polyp and take it out in the same visit. Every other option is a detector only.

The U.S. Preventive Services Task Force recommends screening for adults aged 50 to 75, a grade A recommendation, and for adults aged 45 to 49, a grade B recommendation. For ages 76 to 85, it advises clinicians to offer screening selectively, based on the individual.

Accepted schedules include:

• High-sensitivity stool blood test or FIT, every year.
• Stool DNA-FIT, every 1 to 3 years.
• CT colonography, every 5 years.
• Flexible sigmoidoscopy, every 5 years.
• Flexible sigmoidoscopy every 10 years with FIT every year.
• 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 has to be followed by a colonoscopy. Without that step, the screening delivers no benefit at all.

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 usually means starting earlier and screening more often.