Do Colon Polyps Always Put You at Risk for Colon Cancer?

You’ve probably seen the scary news headlines: Colon cancer is increasing among people under age 50. Doctors don’t know why — though they suspect the modern diet has a lot to do with it — but they do know one thing that can predict whether someone will develop cancer.

That thing is colon polyps. Certain types of polyps are more likely to become cancerous, but does that mean all polyps always turn into cancer? Here’s what you need to know.  

What are colon polyps?  

“Polyps are small growths that can occur in the lining of the colon, almost like colon pimples,” says Rachel Issaka, MD, a gastroenterologist and colon cancer specialist at UW Medical Center – Montlake and Fred Hutch Cancer Center.

Polyps form when cells in the colon grow too quickly, but many things can contribute to their growth:

• Environmental factors  
• Smoking or drinking lots of alcohol
• Eating little fiber or lots of red meat
• Not getting much physical activity
• Having inflammatory bowel disease (IBD), like ulcerative colitis or Crohn’s disease
• Having diabetes  
• Inheriting a genetic condition such as Lynch syndrome or familial adenomatous polyposis
• Age (older than 45)
• Having obesity

Anyone can develop cancer from polyps, but because of healthcare disparities, Black people are more likely to be diagnosed with colorectal cancer at a more advanced stage, in part because precancerous polyps are less likely to be detected and removed early.

Most of the time, colon polyps don’t cause symptoms, but they can grow and become large enough that they can cause pain, bleeding or obstruct the bowel. 

Do colon polyps always become cancer?  

Here’s the good news: Most polyps will not become cancer. In fact, only an estimated 5% to 10% will become cancerous. Some polyps even disappear on their own, Issaka says.  

But determining which polyps will lead to cancer — that part is trickier.  

“When we see polyps during a colonoscopy, we don’t know which ones will disappear and which will progress to cancer,” Issaka says.  

There are two main ways doctors classify polyps: neoplastic polyps, which have a higher chance of becoming cancer, and non-neoplastic polyps, which almost never become cancer:  

Neoplastic polyps include adenomas, sessile serrated lesions and traditional serrated adenomas.

Non-neoplastic polyps include hyperplastic polyps, Hamartomatous polyps (more common in kids) and inflammatory pseudopolyps (in people with IBD).

Doctors can only determine what type of polyps you have by removing them during a colonoscopy and examining them under a microscope, which is why gastroenterologists usually remove polyps during a colonoscopy; they don’t want to leave behind something that could become cancerous.  

How do I know if I have polyps?  

If you have polyps, you probably won’t know unless you get a colonoscopy.

“When polyps are found during a procedure like a colonoscopy, we’re going to remove them and check them for cancer,” Issaka says.

That’s regardless of the size of the polyps and whether you have any symptoms or risk of cancer. A pathologist will examine the polyps and determine if they’re cancerous. If they are, your doctor will probably recommend additional testing or treatment. Even if the polyps aren’t cancerous, you may need to get colonoscopies more frequently.  

If you’re concerned about polyps, talk with your doctor. Screening for colon cancer typically happens after age 45, but if you have a family history of or risk factors for colon cancer or polyps, getting screened sooner may be a good idea.  

“A lot of times, people only know their family history of colon cancer, but they don’t know if any of their family members have had colon polyps,” Issaka says. “But it’s worth learning about, because if your immediate family members have had polyps, we might want to monitor you more closely.”

Talk with your doctor if you’re concerned — but remember, even if you end up having polyps, most polyps won’t become cancerous. And if they do, it’s better to catch the cancer earlier and treat it before it progresses.