Laparoscopic vs. open mesorectal excision for rectal cancer: Are these approaches still comparable? A systematic review and meta-analysis

Background: To analyze pathologic and perioperative outcomes of laparoscopic vs. open resections for rectal cancer performed over the last 10 years. Methods: A systematic literature search of the following databases was conducted: Cochrane Central Register of Controlled Trials, MEDLINE (through PubMed), EMBASE, and Scopus. Only articles published in English from January 1, 2008 to December 31, 2018 (i.e. the last 10 years), which met inclusion criteria were considered. The review only included articles which compared Laparoscopic rectal resection (LRR) and Open Rectal Resection (ORR) for rectal cancer and reported at least one of the outcomes of interest. The analyses followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement checklist. Only prospective randomized studies were considered. The body of evidence emerging from this study was evaluated using the Grading of Recommendations Assessment Development and Evaluation (GRADE) system. Outcome measures (mean and median values, standard deviations, and interquartile ranges) were extracted for each surgical treatment. Pooled estimates of the mean differences were calculated using random effects models to consider potential inter-study heterogeneity and to adopt a more conservative approach. The pooled effect was considered significant if p <0.05. Results: Five clinical trials were found eligible for the analyses. A positive involvement of CRM was found in 49 LRRs (8.5%) out of 574 patients and in 30 ORRs out of 557 patients (5.4%) RR was 1.55 (95% CI, 0.99-2.41; p = 0.05) with no heterogeneity (I2 = 0%). Incorrect mesorectal excision was observed in 56 out of 507 (11%) patients who underwent LRR and in 41 (8.4%) out of 484 patients who underwent ORR; RR was 1.30 (95% CI, 0.89-1.91; p = 0.18) with no heterogeneity (I2 = 0%). Regarding other pathologic outcomes, no significant difference between LRR and ORR was observed in the number of lymph nodes harvested or concerning the distance to the distal margin. As expected, a significant difference was found in the operating time for ORR with a mean difference of 41.99 (95% CI, 24.18, 59.81; p <0.00001; heterogeneity: I2 = 25%). However, no difference was found for blood loss. Additionally, no significant differences were found in postoperative outcomes such as postoperative hospital stay and postoperative complications. The overall quality of the evidence was rated as high. Conclusion: Despite the spread of laparoscopy with dedicated surgeons and the development of even more precise surgical tools and technologies, the pathological results of laparoscopic surgery are still comparable to those of open ones. Additionally, concerning the pathological data (and particularly CRM), open surgery guarantees better results as compared to laparoscopic surgery. These results must be a starting point for future evaluations which consider the association between ''successful resection" and long-term oncologic outcomes. The introduction of other minimally invasive techniques for rectal cancer surgery, such as robotic resection or transanal TME (taTME), has revealed new scenarios and made open and even laparoscopic surgery obsolete.