Endoscopic Submucosal Dissection and Transanal Endoscopic Microsurgery in the Treatment of Rectal Neuroendocrine Tumors: Systematic Review and Meta-Analysis of the Observational Studies.

[INTRODUCTION] Rectal neuroendocrine tumors (rNETs) are subepithelial lesions with potential of malignancy. Despite the guidelines recommending that rNETs measuring 10-20 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 ESD and TEM regarding method effectiveness and safety in the treatment of rNETs.

[METHODS] PubMed/MEDLINE/Embase/EBSCO/CINAHL was searched up for observational studies analyzing the efficacy and safety of both methods in the treatment of rNETs.

[RESULTS] A total of 59 observational studies with a total of n = 2,804 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 (event rate [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.

[DISCUSSION] The efficacy of TEM is higher than ESD with a higher risk of complications in 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.