From the Guidelines
The next step in managing a 25-mm, non-pedunculated lesion in the ascending colon with a history of adenomatous polyps is endoscopic resection, specifically piecemeal endoscopic mucosal resection (PEMR) or endoscopic submucosal dissection (ESD), as recommended by the most recent guidelines 1.
Key Considerations
- The lesion's size and non-pedunculated nature require complete removal with clear margins to prevent recurrence and allow for thorough histopathological examination.
- The procedure should be performed by an experienced endoscopist who specializes in advanced polypectomy techniques.
- Prior to the procedure, the patient should undergo bowel preparation and may require conscious sedation or monitored anesthesia care.
- During the procedure, the endoscopist will inject fluid beneath the lesion to create a cushion, then remove it in one piece (ESD) or piecemeal fashion (PEMR) depending on technical considerations.
Rationale
- Lesions of this size have a higher risk of harboring cancer (approximately 10-15%), and complete removal is essential for both diagnostic and therapeutic purposes 1.
- The Chinese Society of Clinical Oncology (CSCO) guidelines recommend PEMR or ESD for mucosal or submucosal adenomas larger than 20 mm 1.
- The US Multi-Society Task Force on Colorectal Cancer also recommends EMR as the preferred treatment method for large non-pedunculated colorectal lesions 1.
Post-Procedure Care
- The removed tissue must be sent for pathological examination to determine if there are any high-grade dysplastic changes or early malignancy.
- Following resection, surveillance colonoscopy should be scheduled based on the histology findings, typically within 1 year if removed piecemeal or if high-risk features are present 1.
From the Research
Management of Non-Pedunculated Colorectal Polyps
The management of a 25-mm, non-pedunculated lesion in the ascending colon, given a history of adenomatous colon polyps, is primarily guided by endoscopic techniques due to their efficacy, safety, and cost-effectiveness compared to surgical interventions 2, 3, 4.
Endoscopic Mucosal Resection (EMR)
For large (≥20 mm) non-pedunculated adenomatous polyps, conventional (diathermy-based) endoscopic mucosal resection (EMR) is strongly recommended 2. EMR is considered the first-line management strategy for most large non-pedunculated colorectal polyps, which are mostly benign 4.
Alternatives to Conventional EMR
Alternatives to conventional EMR include underwater EMR, which can be considered for the treatment of adenomatous large non-pedunculated colorectal polyps (LNPCPs) 2, and endoscopic submucosal dissection (ESD), which may be suggested in selected cases and in high-volume centers 2. Underwater EMR has shown superiority over conventional EMR in terms of en bloc resection rates, R0 resection rates, and procedure time for large colorectal lesions 5.
Procedure for the Given Lesion
Given the size (25 mm) and non-pedunculated nature of the lesion, the most appropriate next step would involve endoscopic mucosal resection. Considering the options provided:
- A) Endoscopic mucosal resection in piecemeal fashion is a viable approach for large lesions that cannot be removed en bloc, especially if the lesion is too large for en bloc resection or if the equipment for underwater EMR or ESD is not available.
- B) Surgical resection is generally reserved for lesions with suspected invasive cancer or those that cannot be safely removed endoscopically.
- C) Tattooing distal to the lesion and referral for en bloc endoscopic resection might be considered if the lesion is deemed suitable for en bloc resection but requires specialized techniques or equipment not available at the initial procedure.
- D) Argon plasma coagulation (APC) is typically used for ablation of residual tissue or for treating bleeding, rather than primary resection of large polyps.
Based on the provided evidence and considering the size and nature of the lesion, endoscopic mucosal resection is the most appropriate next step. The specific technique (conventional EMR, underwater EMR, or ESD) would depend on the availability of equipment, the expertise of the endoscopist, and the specific characteristics of the lesion. Among the given options, A) Endoscopic mucosal resection in piecemeal fashion seems the most directly relevant to the management of a 25-mm non-pedunculated lesion, acknowledging that en bloc resection is preferable when feasible 2, 6, 5.