What Is A Precancerous Polyp And How Does It Turn Into Cancer?

19 June 2015

Jaime Allen

If you're nearing age 50, or if you have certain types of intestinal ailments like inflammatory bowel disease, you have likely heard that you need to have a colonoscopy screening. During this screening process, a gastroenterologist, like those at Clinical Gastrointestinal Associates, PC, examines the length of your colon, or large intestine, to identify any growths that could become cancer.

How do colorectal growths form?

The large intestine has five layers. Starting from the inside, they are:

Mucosa - inside layer where nutrients are absorbed
Muscularis mucosa - barrier between mucosa and submucosa
Submucosa - contains blood vessels that deliver blood and carry digested nutrients out
Muscularis propria - moves food through the intestinal tract
Serosa - outside layer

Most polyps form in the mucosa, or inside layer. The good news is that these are the easiest to remove, before they grow into other layers of the intestine. That's one reason why colonoscopy screening is important.

Why do the polyps grow?

Polyps grow because you are older or genetically predisposed to have polyps, or because you have a disease that might enhance their growth. Studies have shown it can be helpful to have a healthy diet with plenty of fiber to discourage polyp growth.

What types of growths are the doctors looking for?

There are two ways to look at a "precancerous" polyp, or growth.

The first is that a regular polyp develops abnormal cells and evolves into cancer. In this case, it is best to remove the polyps before they can become cancerous, just to be safe.

In the second, there are two types of polyps in the colon. One is cancerous and one is not. The type identified as precancerous is called an adenomatous growth, and usually does evolve into cancer. The non-cancerous polyps are called hyperplastic and don't carry an added cancer risk.

The problem is that, during the colonoscopy procedure, the doctor is already in a position to remove small polyps. These can be analyzed for cancerous potential, but there is no easy way to know until the polyp is removed and a biopsy performed. So in most routine colonoscopies, small polyps are removed.

If the doctor finds a larger growth than expected, you may need to have a more in-depth colonoscopy procedure or surgery in order to identify and remove the polyp. At that point, you will have a better idea of whether the polyp is cancerous or not based on a biopsy of the tissue taken during your initial screening procedure.

Can removing a polyp lead to more polyps forming?

In some individuals, even when polyps are removed, more will form over time. That's why, if you have ever been shown to have precancerous polyps, your doctor might recommend more frequent colonoscopies or other screening tests to make sure you are not developing more or larger polyps.

If your doctor recommends that you have a colonoscopy screening, it is important to have the procedure done. Delaying it could mean the difference between a small polyp that can be easily removed and tested during your screening, or a larger growth that requires more concern and possibly surgical removal.

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