Endoscopic submucosal dissection and transanal endoscopic microsurgery in the treatment of rectal neuroendocrine tumors. Systematic review and meta-analysis of the observational studies.

Background: Rectal neuroendocrine tumors(rNETs) are subepithelial lesions with potential of malignancy. Despite, the guidelines recommending that rectal neuroendocrine tumors measuring 10 to 20 mm should be removed either endoscopic submucosal dissection (ESD) or transanal endoscopic microsurgery (TEM), the management with these entities is still a clinical dilemma. We performed a meta-analysis to compare endoscopic submucosal dissection and transanal endoscopic microsurgery in terms of method effectiveness and safety in the treatment of rectal neuroendocrine tumurs.

Methods: PubMed/MEDLINE/Embase/Ebsco/Cinahl were searched up for observational studies analysing the efficacy and safety of both methods in the treatment of rectal neuroendocrine tumors.

Results: A total of 59 observational studies with a total of n=2804 participants were included. In a subgroup analysis we demonstrated that the R0 resection rate was significantly (p=0.002) lower for ESD (rate:0.854) than for TEM (0.924). The recurrence rate differed significantly (p=0.008); the lowest (ER =0.015) was found for ESD and the highest for TEM (ER=0.035). The overall bleeding rate was 0.046 and perforation rate was 0.023 and no significant differences (p=0.274 for bleeding, p=0.808 for perforation) were found by intervention type. The rate of other complications (wound dehiscence, soilage, incontinence, rectovaginal fistula, pelvic pain, retroperitoneal emphysema, coagulation syndrome) was significantly (p=0.000) higher for TEM (ER=0.107) than ESD (ER =0.013). We also included 4 comparative studies with 490 patients. Using random effects analysis, we found that the risk ratio for R0 resection was approximately 10% lower for ESD. Our analysis showed significantly greater size (p=0.01), and follow-up (p=0.03) in the group treated with TEM.

Conclusions: The efficacy of TEM is higher than ESD with a higher risk of complications of this method. Lesions with a greater size are treated with TEM and recurrence rate is greater for this procedure. Long follow-up is needed after the treatment of rNETs to detect the recurrence early.