If polyps removed during a colonoscopy are cancerous, the tissue is sent for lab analysis; if cancer is confirmed, doctors check if all cancer was removed (clear margins) and perform further imaging to see if it spread, potentially leading to more surgery (like colectomy), chemotherapy, or radiation for advanced cases, or simply closer surveillance if caught early. The next steps depend on the polyp's features and cancer stage, but often involve follow-up colonoscopies at shorter intervals.
If the cancer has not spread then the doctor may suggest removing the cancerous polyps, usually through a colonoscopy. If the cancer has spread to the muscles surrounding the colon, the doctor may opt for a colectomy. This involves removing part or all of the colon.
“If a polyp that is removed contains cancer, your doctor will usually recommend you get additional imaging tests done to make sure that the cancer has not spread outside of the colon,” said Dr. Kamath.
With that said, the vast majority of polyps are harmless. Experts estimate that only 5-10% of colon polyps will eventually progress and become cancerous (malignant). This gradual process typically takes place over 10 to 15 years, often after age 50.
Once the cancer type has been identified, patients will have additional scans to determine the full extent of their disease. Then, they'll meet with a surgeon to discuss possible treatment plans.
Symptoms
In most cases, no. Your doctor can't usually tell, simply by looking at a polyp during a colonoscopy, if it's cancerous. But if a polyp is found during your colonoscopy, your doctor will remove it and send it to a lab for a biopsy to check for cancerous or precancerous cells.
Cancer that starts as polyp is classified as Stage I of colon cancer. The innermost layer lining the colon or rectum harbors abnormal cells that have expanded into the second layer of the tissue (submucosa).
First, those polyps will be removed. So, if they are precancerous, that cancer will never develop. A colonoscopy, which is usually done under sedation, involves the insertion of a long, flexible tube through the anus and into the rectum and colon.
Minimally invasive surgery.
Polyps that are too large or that can't be removed safely during colonoscopy are usually removed surgically. This is often done by placing an instrument called a laparoscope into the abdomen to remove the part of the bowel with the polyp or cancer.
Pain. A large colon polyp or cancer can block part of the bowel, leading to cramping and belly pain. Rectal bleeding. This can be a sign of colon polyps, cancer or other conditions, such as hemorrhoids or minor tears of the anus.
Participants with low-risk polyp(s) are recommended to return to screening with colonoscopy in five years. Participants with high-risk polyp(s) are recommended to return to screening with colonoscopy in three years.
Before you go home, your doctor tells you if they've removed any polyps or taken any biopsies from your bowel. The biopsy results can take up to 2 weeks. Your specialist writes to you with the results. If your GP referred you for the test, they should also receive a copy.
Studying colorectal polyps
In total, forty patients were tracked after undergoing routine colonoscopies and biopsies of colorectal polyps. An increased presence of a common gut bacteria, called Bacteroides fragilis, in mucosal biopsies was found to indicate a higher risk of colon polyps becoming cancerous.
After a cancerous polyp is identified, further evaluation is necessary to assess the stage of the cancer. This may include: Imaging Studies: Tests such as CT scans or MRIs may be performed to check for any spread of cancer beyond the polyp.
During a colonoscopy, your doctor may take a small tissue sample — called a biopsy — from your colon lining. This is typically done if anything abnormal is seen, such as a polyp, inflammation, or an unusual area that needs further evaluation. A colonoscopy with biopsy does not necessarily mean you have cancer.
However, most colonoscopy screenings don't result in a cancer finding. If your doctor does find a suspicious lesion, such as a polyp, they remove it immediately during the colonoscopy before it turns into cancer. Your doctor can also take tissue samples for analysis to diagnose anything more serious.
Precancerous polyps are those that can become cancerous over time if they aren't removed. The most common polyps are tubular adenomas, sessile serrated adenomas and hyperplastic polyps. These names are based on what the polyps' cells look like under a microscope.
You may be at a higher risk of developing colon cancer if you have:
A polyp can take as many as 10 to 15 years to develop into cancer. With a colonoscopy, doctors can find and remove polyps before they have the chance to turn into cancer.
Level 3 indicates cancer cells invading any part of the stalk and level 4 signifies cancer cells invading into the submucosa of the bowel wall below the stalk of the polyp but above the muscularis propria. All sessile polyps with any degree of invasion were defined as level 4 (Figure 1).
Cancer is known to occur more frequently in larger polyps. In the St. Marks Hospital experience, cancer was present in about 1% of adenomas smaller than 1 cm, 10% of 1–2 cm adenomas, and nearly 50% of adenomas larger than 2 cm (2).
After the endoscopy and anesthesia procedure, patients should not drive and should have a family member accompany them. Take medications exactly as prescribed by the doctor. After polyp removal, patients should rest, avoid heavy work, and refrain from excessive physical activity.
Polyps are common in American adults, and while many colon polyps are harmless, over time, some polyps could develop into colon cancer. While the majority of colon cancers start as polyps, only 5-10% of all polyps will become cancerous. The size of a polyp typically does make a difference.
If a polyp is removed completely, it is unusual for it to return in the same place. The same factors that caused it to grow in the first place, however, could cause polyp growth at another location in the colon or rectum. New polyps will develop in at least 30 percent of people who have previously had polyps.