Endoscopic submucosal dissection in tumors extending to the dentate line compared to proximal rectal tumors: a systematic review with meta-analysis

Endoscopic submucosal dissection (ESD) is a validated treatment for early rectal tumors, but whether this therapy is efficient or not for rectal tumors extending to the dentate line (RTDL) remains unclear. We performed a systematic review and meta-analysis to assess the effectiveness and safety of ESD in RTDL compared to non-RTDL. A search in PubMed, Scopus and the Cochrane library up to April 2020 was conducted to identify studies that compared ESD in both localizations (RTDL and non-RTDL), reporting at least one main outcome (en bloc, complete resection, recurrence). Secondary outcomes were adverse event occurrence. Five observational studies including 739 patients with a total of 201 RTDL and 538 non-RTDL were considered. The proportion of female sex (66% vs. 36.9%, P < 0.001) and tumor size [mean difference = 7.75, 95% confidence interval (CI): 3.01-12.49, P = 0.001] were higher in the RTDL group. There were no differences in en bloc resection rates between RTDL and non-RTDL groups [odds ratio (OR): 0.95, 95% CI: 0.50-1.79, P = 0.087]. The complete resection rate was significantly higher in the non-RTDL group (OR: 1.72, 95% CI: 1.18-2.53, P = 0.005, I-2 = 0%). However, recurrence rates were comparable (RD: -0.04, 95% CI: -0.07 to 0.00, P = 0.06, I-2 = 0%). Concerning adverse events, there were no differences in terms of perforation (OR: 0.9, 95% CI: 0.26-3.08, P = 0.86, I-2 = 0%) or delayed bleeding (OR: 0.64, 95% CI: 0.17-2.42, P = 0.51, I-2 = 35%). Anal pain rate was 28% (95% CI: 21.4-35.8%). ESD is an effective and safe therapeutic approach for RTDL with comparable recurrence rate to non-RTDL. The lower complete resection rate in RTDL needs to be clarified in studies.