Colon polyps are abnormal growths that develop on the inner lining of the large intestine. These growths vary in size but are generally not cancerous themselves. However, certain types have the potential to develop into colorectal cancer over many years if they are not removed. For most patients, polyps are removed without traditional surgery using specialized endoscopic procedures performed during a standard outpatient colonoscopy.
Endoscopic Removal Techniques
The standard non-surgical approach is polypectomy, which uses the flexible colonoscope inserted through the rectum to reach the entire colon. For very small polyps, typically five millimeters or less, cold snare polypectomy (CSP) is often preferred. This technique uses a thin wire loop, or snare, to cut the polyp away without electrical current. This offers a high rate of complete removal with minimal risk of complications, such as thermal injury to the colon wall.
For polyps between six and nine millimeters, standard snare polypectomy, sometimes using electrocautery (heated energy), is applied to cut the polyp and seal blood vessels at the base. Larger polyps, particularly those measuring 20 millimeters or more, or those that are flat, require more advanced endoscopic techniques for complete removal. While historically these larger lesions often required major surgery, they are now routinely managed endoscopically.
A common method for removing large, flat polyps is Endoscopic Mucosal Resection (EMR). This procedure involves injecting a fluid solution underneath the polyp to lift it away from the deeper muscle layers of the colon wall. This fluid cushion provides a safer margin for the endoscopist to use a snare to remove the growth, often in multiple pieces, a technique known as piecemeal resection.
The most technically demanding endoscopic option is Endoscopic Submucosal Dissection (ESD), reserved for very large or complex lesions, including some early-stage cancers. ESD involves using a specialized electrosurgical knife to meticulously cut the polyp out in a single, intact piece, rather than multiple fragments. Removing the polyp in one piece, known as en bloc resection, allows the pathologist to accurately assess the margins and determine if the lesion has been completely excised.
Factors Governing Non-Surgical Feasibility
While most polyps can be removed endoscopically, certain characteristics may necessitate traditional surgical removal, known as a colectomy. The size and morphology (shape) of the polyp are primary considerations for determining feasibility. Polyps with a stalk (pedunculated polyps) are typically easier to remove endoscopically than flat (sessile) polyps, which have a broad base attached directly to the colon wall.
Polyps larger than 20 millimeters present a higher degree of difficulty for endoscopic removal and correlate with an increased risk of containing cancer. The location of the polyp can also complicate the procedure. Lesions situated in narrow sections of the colon or near critical structures like the appendix may be difficult to access safely with the colonoscope. Additionally, the wall of the right colon is thinner than the left, making the endoscopic removal of large polyps in that area riskier.
The most significant factor determining the need for surgery is the depth of invasion found in the pathology report. Endoscopic removal is curative only for polyps confined to the superficial layers of the colon wall (the mucosa and upper submucosa). If the pathologist determines cancer cells have invaded deeply into the submucosa (typically more than 1000 micrometers), or if the polyp exhibits high-risk features, traditional surgery is generally required. High-risk features include poorly differentiated cells or invasion into blood or lymph vessels. These features suggest a higher probability that cancer cells may have spread to nearby lymph nodes, which cannot be removed endoscopically.
Post-Removal Management and Surveillance
After the successful endoscopic removal of a colon polyp, subsequent management is driven by the final pathology results. The pathologist examines the removed tissue to determine the polyp type, size, and presence of any high-grade changes or malignancy. These findings are used to stratify the patient’s risk of developing future polyps or cancer.
Patients who had polyps with high-risk features are typically placed on an accelerated surveillance schedule. High-risk features include multiple growths, any adenoma 10 millimeters or larger, or the presence of high-grade dysplasia. This usually involves a repeat colonoscopy within three years to check for new or recurrent polyps. Conversely, patients with only one or two small, low-risk adenomas may not require another colonoscopy for five to ten years.
Patients can also play an active role in preventing future polyp formation by adopting healthy lifestyle habits. Recognized actions that help reduce the risk of developing new polyps include:
- Maintaining a diet rich in fiber and low in red and processed meats.
- Engaging in regular physical activity.
- Avoiding both smoking and excessive alcohol consumption.
Following the individualized surveillance schedule provided by a physician is necessary to ensure any new growths are identified and removed early.