Polyps develop in two main shapes. Sessile polyps grow flat on the tissue lining the organ. Sessile polyps can blend in with the lining of the organ, so they’re sometimes tricky to find and treat. Sessile polyps are considered precancerous. They’re typically removed during a colonoscopy or follow-up surgery.
Pedunculated polyps are the second shape. They grow on a stalk up from the tissue. The growth sits atop a thin piece of tissue. It gives the polyp a mushroom-like appearance.
Sessile polyps come in several varieties. Each is a bit different than the others, and each carries with it the risk of cancer.
Sessile serrated adenomas
Sessile serrated adenomas are considered precancerous. This type of polyp gets its name from the sawlike appearance the serrated cells have under the microscope.
This type of polyp is commonly detected in a colon cancer screening. It carries a high risk of becoming cancerous. They can be pedunculated, but they’re commonly sessile.
The majority of colon polyps are adenomatous, or tubular adenoma. They can be sessile or flat. These polyps carry a lower risk of becoming cancerous.
Many adenomas have a mixture of both growth patterns (villous and tubular). They’re referred to as tubulovillous adenomas.
It’s unclear why polyps develop when they’re not cancerous. Inflammation may be to blame. A mutation in the genes that line the organs may play a role, too.
Sessile serrated polyps are common among women and people who smoke. All colon and stomach polyps are more common in people who:
- are obese
- eat a high-fat, low-fiber diet
- eat a high-calorie diet
- consume large amounts of red meat
- are 50 years old or older
- have a family history of colon polyps and cancer
- use tobacco and alcohol regularly
- aren’t getting enough exercise
- have a family history of type 2 diabetes
Polyps are almost always found during a colon cancer screening or colonoscopy. That’s because polyps rarely cause symptoms. Even if they’re suspected before a colonoscopy, it takes the visual exam of the inside of your organ to confirm the presence of a polyp.
During a colonoscopy, your doctor will insert a lighted tube into the anus, through the rectum, and into the lower large intestine (colon). If your doctor sees a polyp, they may be able to remove it entirely.
Your doctor may also choose to take a sample of the tissue. This is called a polyp biopsy. That tissue sample will be sent to a lab, where a doctor will read it and make a diagnosis. If the report comes back as cancerous, you and your doctor will talk about treatment options.
Benign polyps don’t have to be removed. If they’re small and not causing discomfort or irritation, your doctor may choose to just watch the polyps and leave them in place.
You may need more frequent colonoscopies to watch for changes or additional polyp growth, however. Likewise, for peace of mind, you may decide you want to reduce the risk of the polyps becoming cancerous (malignant) and remove them.
Cancerous polyps need to be removed. Your doctor can remove them during the colonoscopy if they’re small enough. Larger polyps may need to be removed with surgery at a later point.
Not every sessile polyp will become cancerous. Only a small minority of all polyps become cancerous. That includes sessile polyps.
However, sessile polyps are a greater cancer risk because they’re tricky to find and may be overlooked for years. Their flat appearance hides them in the thick mucus membranes that line the colon and stomach. That means they may become cancerous without ever being detected. This may be changing, however.
Removing polyps will reduce the risk of the polyp becoming cancerous in the future. This is an especially good idea for serrated sessile polyps. According to one study, 20 to 30 percent of colorectal cancers come from serrated polyps.
If you’re preparing for a colonoscopy or colon cancer screening, talk with your doctor about your risk for colon cancer and what will be done if polyps are found. Use these talking points to start the conversation:
- Ask if you’re at an increased risk of colon cancer. Lifestyle and genetic factors may influence your risk for developing colon cancer or precancer. Your doctor can talk about your individual risk and things you can do to lower your risk in the future.
- Ask about polyps after the screening. In your follow-up appointment, ask your doctor about the results of the colonoscopy. They’ll likely have images of any polyps, and they’ll also have results of biopsies back within a few days.
- Talk about next steps. If polyps were found and tested, what needs to happen to them? Talk with your doctor about a treatment plan. This may include a watchful waiting period where you don’t take action. If the polyp is precancerous or cancerous, your doctor may want to remove it quickly.
- Reduce your risk for future polyps. While it’s unclear why colon polyps develop, doctors do know you can lower your risk by eating a healthy diet with fiber and reduced fat. You can also reduce your risk for polyps and cancer by losing weight and exercising.
- Ask when you should be screened again. Colonoscopies should start at age 50. If your doctor doesn’t find any adenomas or polyps, the next screening may not be necessary for 10 years. If small polyps are found, your doctor may suggest a return visit in as little as five years. However, if larger polyps or cancerous polyps are found, you may need several follow-up colonoscopies in the span of a few years.