If you’ve had colon polyps removed during a colonoscopy, you may be wondering what happens if the biopsy results show the polyps are precancerous. Precancerous polyps, also called adenomas, are polyps that have the potential to become cancerous over time if they are not removed. This article will walk through what precancerous polyp results mean, what the next steps are, and what you can expect if you have precancerous colon polyps.
What are precancerous polyps?
Precancerous polyps, also known as adenomatous polyps or adenomas, are growths in the colon or rectum that have the potential to become cancer. Adenomatous polyps have cellular abnormalities and genetic mutations that distinguish them from benign hyperplastic polyps, which have very little chance of becoming cancerous.
There are a few different types of precancerous polyps:
- Tubular adenoma – Most common, with a glandular, tube-like structure
- Tubulovillous adenoma – Contains both glandular and villous structures, with small projections on the surface
- Villous adenoma – Least common, with numerous villi along the surface and a higher cancer risk
- Sessile serrated adenoma – Flat with a serrated, or sawtooth pattern; found on the right side of the colon
The main distinguishing factor of a precancerous polyp is that the cells look abnormal under the microscope. While not yet cancer, these abnormal cells can slowly turn into cancer over the course of usually 5-10 years.
Grading of precancerous polyps
Pathologists grade precancerous polyps based on the degree of dysplasia, or abnormality, of the cells:
- Low-grade dysplasia: Mildly abnormal cells
- High-grade dysplasia: Moderately to severely abnormal cells
- Carcinoma in situ: Severely abnormal cells on the verge of becoming invasive cancer
Higher grades of dysplasia, particularly high-grade dysplasia or carcinoma in situ, have a higher risk of progressing to cancer over time. The larger the precancerous polyp, the higher the chance it contains advanced precancerous features.
What happens when polyp results show precancerous changes?
If your colon polyp biopsy comes back showing precancerous changes of any grade, your doctor will recommend you have more frequent colonoscopies to monitor for any progression. How often you need follow-up colonoscopies depends on the number, size, location, and degree of dysplasia of the polyps.
Typical follow-up recommendations if you have had precancerous colon polyps removed are:
- Low-grade dysplasia: Repeat colonoscopy in 5-10 years
- High-grade dysplasia: Repeat colonoscopy in 3 years
- Carcinoma in situ: Repeat colonoscopy in less than 3 years
- Multiple precancerous polyps: Repeat colonoscopy in less than 3 years
- Large (over 1 cm) precancerous polyp: Repeat colonoscopy in less than 3 years
The main goal of increased surveillance with frequent colonoscopies is to find and remove any new polyps before they have the chance to turn cancerous. You and your doctor may also discuss whether chemoprevention with aspirin or other NSAIDs might be appropriate to try to prevent new polyps from forming.
What if polyps are not able to be completely removed?
If a precancerous polyp is identified during colonoscopy but unable to be fully removed, such as if it is located in an area difficult to access, additional procedures may be recommended to try to completely take out the polyp and prevent cancer progression. Options may include:
- Repeat colonoscopy to try to fully remove the polyp
- Endoscopic mucosal resection (EMR) to remove larger, flatter lesions
- Endoscopic submucosal dissection (ESD) to dissect below the polyp and cut it away from the wall of the colon
- Surgery to remove the section of colon containing the precancerous polyp
Can precancerous colon polyps turn into cancer?
Yes, precancerous colon polyps can definitely turn into colorectal cancer over time if they are not removed. How quickly adenomas turn into cancer depends on multiple factors, including:
- Type of polyp: Villous adenomas progress to cancer faster than tubular adenomas.
- Grade of dysplasia: Higher grade dysplasia means the cells are closer to becoming cancer.
- Size: Larger polyps are more likely to advance to cancer.
- Number: Having multiple adenomas increases risk.
- Family history: Precancerous polyps progress faster in some families with high hereditary risk.
While it is not possible to predict exactly which polyps will become cancerous, it is estimated that it takes about 10-15 years for an adenomatous polyp to transform into colorectal cancer if it is not removed. Catching and removing precancerous polyps early through colonoscopy screening is the best way to prevent cancer.
What are the risk factors for developing precancerous polyps?
There are several important risk factors that make someone more likely to develop precancerous adenomatous polyps in the colon and rectum:
- Age: Risk increases after age 50.
- Family history: Having a first-degree relative (parent, sibling, child) with colorectal polyps or cancer increases risk.
- Genetic syndromes: Inherited conditions like familial adenomatous polyposis (FAP) greatly increase risk.
- Inflammatory bowel disease: Chronic inflammation from Crohn’s or ulcerative colitis is a risk factor.
- Obesity and dietary factors: Being obese, eating a diet high in red meat and processed foods, and low in fiber, fruits, and vegetables may increase risk.
- Smoking and alcohol: Current and heavy use increase adenoma risk.
- Diabetes: Having type 2 diabetes is linked with a higher risk of precancerous colon polyps.
Talk to your doctor about whether you should begin colonoscopy screening for colon polyps and cancer earlier than age 50 based on your risk factors.
What are the signs and symptoms of precancerous polyps?
The vast majority of precancerous polyps do not cause any signs or symptoms. This is why getting regular screening colonoscopies is essential to find and remove these precancerous growths before they have the chance to turn into cancer. Rarely, larger adenomas may cause symptoms like:
- Rectal bleeding
- Blood in the stool
- Changes in bowel habits
- Abdominal pain
- Feeling that the bowel doesn’t empty completely
If you develop any persistent gastrointestinal symptoms, make sure to follow up with your doctor to discuss whether colonoscopy is recommended to determine the cause.
How are precancerous colon polyps diagnosed?
Precancerous adenomatous polyps are most often diagnosed during a screening or diagnostic colonoscopy. Colorectal polyps may sometimes initially be spotted on another imaging test, like CT colonography or flexible sigmoidoscopy, that leads to the recommendation to get a full colonoscopy.
During colonoscopy, polyps can be removed by passing a wire loop through the colonoscope tube to cut the polyp off the wall of the colon. The polyp is then sent to the pathology lab for biopsy analysis under the microscope to determine if it is precancerous adenoma or benign hyperplastic tissue.
The pathology report will specify details about polyp size, location, morphology, grade of dysplasia, and completeness of removal. Follow-up colonoscopy timing and recommendations are based on interpreting this pathology report.
How are precancerous colon polyps treated or removed?
The standard treatment for precancerous adenomatous colon polyps is surgical removal, most often during colonoscopy. There are a few techniques and tools that can be used:
- Polypectomy snare: A wire loop passed through the colonoscope to encircle the polyp and cut it off from the intestinal wall.
- Endoscopic mucosal resection: Removal of larger, flatter polyps using special tools.
- Electrocautery: Applying electric current through the colonoscope to burn off small polyps.
- Underwater endoscopic resection: Lifting polyps with water for easier resection.
Larger polyps that cannot be fully removed endoscopically may require surgery to remove that portion of the colon. Rarely, endoscopic submucosal dissection (ESD) can be considered to dissect beneath very large polyps so they can be removed endoscopically rather than with open surgery.
After polyp removal, the colonoscopy site is monitored for any bleeding or other complications. Most patients can go back to their usual activities the same day.
What happens if precancerous colon polyps are not removed?
If precancerous adenomas are left in place and not removed, they have a high likelihood of slowly progressing to colorectal cancer over the next 5-15 years. Unremoved precancerous polyps can acquire additional cancer-promoting genetic mutations and become invasive cancers over time.
This is why following expert recommendations for repeat surveillance colonoscopies to find and remove any new adenomas is so important after having precancerous polyps detected. Frequent colonoscopy is needed to intervene before polyps become cancerous.
What are the outlook and survival rates if polyps have precancerous changes?
When detected at the precancerous polyp stage, the prognosis is excellent. The 5-year survival rate for isolated precancerous polyps that are fully removed is nearly 100%. Regular surveillance colonoscopies are still needed after removal to make sure new polyps do not develop.
Precancerous polyps only have the potential to turn into cancer if left in place for many years. As long as you undergo recommended repeat colonoscopies at the interval advised by your doctor, there is a very low chance of developing colorectal cancer.
Studies show that colonoscopy with polyp removal reduces the incidence of colorectal cancer by up to 80% and reduces mortality by up to 65%. Early detection and removal of precancerous adenomas saves lives.
What lifestyle changes are recommended if you have had precancerous polyps?
Making certain lifestyle changes may help reduce the risk of developing new adenomas after precancerous polyps have been removed:
- Follow colonoscopy surveillance recommendations. Have follow-up colonoscopies as often as your doctor advises based on your polyp status.
- Quit smoking. Smoking is linked with an increased risk of adenomas.
- Limit alcohol. Heavy alcohol use can increase polyp formation.
- Exercise regularly.Aim for at least 30 minutes of moderate exercise 5 days a week.
- Lose weight if overweight. Obesity is tied to higher colorectal polyp risk.
- Eat more fiber. Aim for 25-30 grams of fiber from fruits, vegetables, and whole grains daily.
- Limit red and processed meat. These are associated with greater polyp development.
- Take a daily aspirin if recommended. Your doctor may suggest aspirin to help prevent adenoma recurrence.
Making these healthy lifestyle modifications may reduce your chances of growing new precancerous polyps.
Can colon cancer develop even if you are getting regular colonoscopies?
Even with regular colonoscopy screening for polyp removal, there is still a small risk of developing colorectal cancer. How often this occurs depends on multiple factors:
- Polyps missed during colonoscopy: Even the best colonoscopies can sometimes miss seeing small or flat polyps in the colon.
- Time between colonoscopies: Cancer risk increases if too much time goes between exams.
- Rapidly growing polyps: Rarely, some polyps grow very quickly between colonoscopies.
- Incomplete polyp removal: If a polyp is not fully excised, any remnants left behind can progress to cancer.
The risk of developing colorectal cancer when getting colonoscopies as recommended is very low. But it is not zero, which is why paying attention to symptoms like rectal bleeding between exams is important.
Can you get colon cancer without having polyps?
Most cases of colorectal cancer arise from initially benign adenomatous polyps that slowly become cancerous over time. However, it is also possible for some colorectal cancers to arise de novo, meaning they develop directly into cancer without going through a precancerous polyp intermediary phase.
How often this happens is not clear. Some research has found up to 50% of colorectal cancers may not develop from adenomas. This highlights the importance of maintaining colonoscopy screening even if you have never had polyps detected.
Summary: Key points about precancerous colon polyps
- Precancerous polyps, or adenomas, are growths with abnormal cellular changes that can slowly turn cancerous over 5-15 years if not removed.
- Larger, more dysplastic polyps, or those with carcinoma in situ, have the highest risk of becoming colon cancer.
- Frequent colonoscopy surveillance is recommended after precancerous polyps are found to check for recurrence.
- Removing precancerous polyps early prevents progression to colorectal cancer in most cases.
- Even with polyp removal, some colorectal cancers can develop between colonoscopies from missed polyps or de novo cancer.
- Symptom monitoring and prompt evaluation remain important even with colonoscopy screening.
Conclusion
Finding out you have precancerous changes in colon polyps can be concerning. But the good news is that recognition and removal of these adenomas prevents most colorectal cancers from developing. By undergoing regular surveillance colonoscopies as recommended by your doctor, the chances of an adenoma progressing to cancer are extremely low.
Colonoscopy is the best way to intervene early in the cancer process by catching precancerous polyps before they have the chance to turn malignant. While screening and polyp removal significantly reduce colorectal cancer risk, maintaining awareness of potential symptom changes remains important as well.
Discuss any specific questions or concerns you have about your colon polyp findings with your gastroenterologist. Adhering to the advised follow-up and lifestyle recommendations can help optimize your health and reduce your risk of colorectal cancer in the future.