What makes colon polyps grow

The vast majority of polyps are NOT cancerous or even pre-cancerous. The polyps without the potential to turn into cancer include small hyperplastic polyps, inflammatory polyps, and hamartomatous polyps which are not part of an inherited polyp syndrome. The precancerous polyp which can turn into a cancer is called an adenoma. The two most common types of colorectal polyps are hyperplastic polyps and adenomas. Usually, the larger the size of the adenoma, the greater the chance that there may be cancer or pre-cancerous cells present in the polyp.

Since it is hard to determine the exact nature of a polyp, polyps found during colonoscopy are removed and sent to the lab for a microscopic analysis. Current theories propose it will take about 10 years for a small adenoma to transform into a cancer. That is why the standard interval for screening colonoscopy is 10 years. However, the time interval may be shorter for patients with a hereditary form of colon cancer like familial adenomatous polyposis or hereditary non polyposis colorectal cancer or inflammatory bowel disease.

The recommended intervals are general guidelines and may not apply to every patient. Most polyps do not produce any symptoms, which is why screening is so important. Rarely, a polyp may cause visible blood to appear in your stool. Sometimes blood will only be detected with special testing your doctor may perform on a stool sample hemoccult testing. Rarely, polyps may cause a change in bowel habits; if the polyp or cancer is very large it may lead to constipation, or perhaps diarrhea, though this is highly unusual.

There appears to be a combination of environmental and hereditary factors that leads to forming polyps. These types of polyps are also known as pseudopolyps because they are not true polyps, but rather develop as a reaction to chronic inflammation in the colon.

Inflammatory polyps are benign and generally do not carry the risk of developing into colon cancer. Approximately 15 percent of polyps detected in colon cancer screening are villous or tubulovillous adenomas.

This type of polyp carries a high risk of turning cancerous. They are commonly sessile, which makes them more difficult to remove. Smaller villous adenoma polyps may be removed during a colonoscopy, while larger polyps of this type may require surgery for complete removal.

Polyps can be detected and safely removed during a colonoscopy, preventing them from turning into cancer. Large polyps may require more than one treatment, and in some patients surgery could be required for complete removal. If you have an increased risk for colon polyps, talk with your doctor about the types and frequency of tests that will be best for you. To schedule an appointment to discuss treatment options for colon and rectal polyps, call us at If there's a cancerous change in the polyp, you may need further treatment depending on the degree and extent of change.

The exact cause of bowel polyps is not known. It's thought they're caused by the body producing too many cells in the lining of the bowel. Bowel polyps are usually found when your bowel is being looked at for another reason or during screening for bowel cancer. If polyps are found, a colonoscopy or CT colonography is needed to view the whole of the large bowel and remove the polyps.

Some people with a certain type of polyp may be at risk of it coming back in the future recurring. Depending on the results of your diagnosis your doctor may recommend you return for further testing in 1 to 5 years.

Page last reviewed: 23 September Next review due: 23 September Bowel polyps. Bowel polyps are very common, affecting around 1 in 4 people aged 50 or over. We refer to adenomatous polyps as pre-cancerous polyps because they are not cancerous yet, but they have the potential to become cancerous. Given enough time to grow and develop, some adenomatous polyps can spread into surrounding tissues and infiltrate the two highway systems of the body: the bloodstream and the lymph nodes.

This ability to invade and spread, or metastasize, is how we define a cancer. Does having a polyp mean that I will get cancer? No, but it does increase your risk. Most polyps — even the adenomatous type — do not turn into cancer. However, nearly all colorectal cancers that do develop start out as polyps. Removing a polyp early makes sure that it will never have the chance to turn into cancer.