The role of a second endoscopic procedure after a failed first endoscopic mucosal resection for colorectal polyps

When faced with a large, nonpedunculated, colon polyp, endoscopists frequently attempt endoscopic mucosal resection (EMR). This includes submucosal injection followed by snare polypectomy, sometimes in a piecemeal fashion, with the goal of complete eradication of the neoplastic lesion and prevention of colorectal cancer. Despite one’s best efforts, this is not always successful, and parts of the polyp are sometimes impossible to resect. Factors that can lead to an unsuccessful EMR include difficult location (such as at flexures or the ileocecal valve), failure to lift the polyp with submucosal injection, position behind a fold, significant looping and challenging scope position, and intraprocedural events, such as bleeding or suspected perforation. When this failure to completely resect a large polyp occurs, the options include re-attempting the resection, referring the patient to an expert endoscopist or, more frequently, exploration of surgical options.

“If an endoscopist attempts EMR and fails because of nonlifting, difficult location or unstable position, a referral to surgery is not necessary in all cases.”

In this issue of Endoscopy, Tate et al. from Australia [1] describe a cohort of patients who had an incomplete resection of large colorectal polyps by EMR at an expert center, but were offered a second attempt to complete the resection endoscopically 1 – 2 months later (two-stage EMR [tsEMR], n = 43). The authors compared these lesions with the ones for which single-stage EMR (ssEMR, n = 1944) was attempted, and with lesions that were referred for surgery after failure of the initial resection (n = 78). The patients who were offered tsEMR rather than surgery were older, and their lesions were less likely to have a dominant Is component (probably a marker of lesion complexity) and less likely to contain high grade dysplasia. The two main reasons for failure of ssEMR were nonlifting of the polyp and difficult endoscopic access. The authors found that when applied to a selected group of patients, tsEMR was successful in the majority of cases, although at a lower rate than for naïve lesions at first EMR attempt (83.7 % vs. 94.9 %; P = 0.01). tsEMR was also associated with a higher rate of recurrent and residual adenoma (39.4 % vs. 13.6 %; P < 0.001), and more cases of recurrence were noted at subsequent follow-up procedures; in most cases, however, residual adenoma was dealt with endoscopically, leading to a long-term success rate of 81.8 % avoiding surgery. A subgroup of 236 patients had a failed attempt at EMR prior to referral to the tertiary center. When compared with the treatment-naïve lesions, those previously attempted had a higher rate of submucosal fibrosis (63.3 % vs. 18.6 %; P < 0.001), were less often resected en bloc (9.2 % vs. 17.8 %; P = 0.002), and had a lower success rate for EMR at the tertiary center (83.1 % vs. 94.9 %; P < 0.01). However, when EMR of those previously manipulated lesions was successful, recurrence rates and referral to surgery were not higher than for treatment-naïve lesions. The main limitation of this study is that the decision to attempt tsEMR or refer to surgery was not randomized. Factors related to the patient, polyp, and endoscopist played a role in this decision, and tsEMR was offered to a highly selected group of patients.

We have learned a lot about difficult colonic polyps in the past few years. Studies have shown that expert endoscopists can successfully deal with many difficult polyps. However, success is negatively affected by previous resection attempts, biopsies or other manipulation of the polyp. Buchner et al. [2] reported on 315 “defiant” colorectal polyps in 287 patients referred to an expert endoscopist. EMR was successful in 286 polyps (91 %), with residual/recurrent neoplasia noted at follow-up in 27 % of cases. Raju et al. [3] described 203 patients with “complex” polyps who were referred to an expert endoscopist as an alternative to surgery. EMR was successful in 76 %, with a very low residual/recurrent adenoma rate of 4 %. Friedland et al. [4] attempted EMR on 38 biopsy-proven benign lesions in 36 patients who were initially referred for surgical resection. EMR was successful in 71 %, but the recurrence rate was 50 %. In all three case series, recurrent/residual neoplastic tissue was usually amenable to endoscopic therapy. Kim et al. [5] confirmed that prior advanced manipulation (partial resection or tattoo) led to a significant decrease in successful endoscopic resection, from 93.5 % to 50 %, while the recurrence rate increased from 7.7 % to 53.8 %. Interestingly, polyps that were biopsied prior to referral were also less amenable to complete endoscopic resection (68.2 %) and had a higher recurrence rate (40.7 %). We have also learned that surgery is not a safe alternative to EMR. Keswani et al. [6] found a high rate (17 %) of complications in a cohort of 359 patients referred for surgical resection of nonmalignant polyps.

What does all this mean to the practicing endoscopist? When one encounters a large colonic polyp, the decision to proceed with endoscopic resection should consider not only size, location, and shape of the polyp, but also more practical factors such as adequate time, availability of equipment, and the experience of the endoscopist and staff. If those factors do not favor endoscopic resection, it is recommended to postpone the procedure to another day/location, and even consider referral to another center or to a more experienced endoscopist, without extensive manipulation of the polyp. Only if the lesion is suspicious should a couple of small biopsies be obtained, but partial snare resection should definitely be avoided. Placement of a submucosal tattoo is appropriate, unless the lesion is in the rectum or cecum; however, the tattoo should always be placed a few centimeters away from the polyp. We learn from Tate et al. [1] that if an experienced endoscopist attempts EMR and fails because of nonlifting, difficult location or unstable position, a referral to surgery is not necessary in all cases. After taking into account many different factors, a second attempt can be offered to motivated patients, who agree with the long-term commitment to multiple procedures. Surgery will continue to play a role in those who are not candidates for tsEMR and for those in whom aggressive endoscopic attempts fail.

It is now clear that the endoscopy community has a significant role to play in the prevention of colorectal cancer by removing almost all precancerous lesions. However, success of this effort requires collaboration with regional referral centers and expert endoscopists for the most advanced and largest lesions on that spectrum.

• References

• 1 Tate DJ, Desomer L, Hourigan LF. et al. Two stage endoscopic mucosal resection is a safe and effective salvage therapy after a failed single-session approach. Endoscopy 2017; 49: 888-898
• 2 Buchner AM, Guarner-Argente C, Ginsberg GG. Outcomes of EMR of defiant colorectal lesions directed to an endoscopy referral center. Gastrointest Endosc 2012; 76: 255-263
• 3 Raju GS, Lum PJ, Ross WA. et al. Outcome of EMR as an alternative to surgery in patients with complex colon polyps. Gastrointest Endosc 2016; 84: 315-325
• 4 Friedland S, Banerjee S, Kochar R. et al. Outcomes of repeat colonoscopy in patients with polyps referred for surgery without biopsy-proven cancer. Gastrointest Endosc 2014; 79: 101-107
• 5 Kim HG, Thosani N, Banerjee S. et al. Effect of prior biopsy sampling, tattoo placement, and snare sampling on endoscopic resection of large nonpedunculated colorectal lesions. Gastrointest Endosc 2016; 81: 204-213
• 6 Keswani RN, Law R, Ciolino JD. et al. Adverse events after surgery for nonmalignant colon polyps are common and associated with increased length of stay and costs. Gastrointest Endosc 2016; 84: 296-303