Rectal neuroendocrine tumors (NETs) are rare, with an incidence of 0.17%, but they represent 12% to 27% of all NETs and 20% of gastrointestinal NETs. Although rectal NETs are uncommon tumors, their incidence has increased over the past few years, and this is probably due to the improvement in detection rates made by advanced endoscopic procedures. The biological behavior of rectal NETs may be different: factors predicting the risk of metastases have been identified, such as size and grade of differentiation. The tendency for metastatic diffusion generally depends on the tumor size, muscular and lymphovascular infiltration, and histopathological differentiation. According to the current European Neuroendocrine Tumor Society (ENETS) guidelines, tumors that are smaller than 10 mm and well differentiated are thought to have a low risk of lymphovascular invasion, and they should be completely removed endoscopically. Rectal NETs larger than 20 mm have a higher risk of involvement of muscularis propria and high metastatic risk and are candidates for surgical resection. There is controversy over rectal NETs of intermediate size, 10–19 mm, where the metastatic risk is considered to be 10–15%: assessment of tumors endoscopically and by endoanal ultrasound should guide treatment in these cases towards endoscopic, transanal, or surgical resection.

Minimally invasive Heller myotomy is considered the gold standard surgical approach for symptomatic achalasia because it is a safe and effective procedure. Over the last years, several studies comparing the laparoscopic and robotic approach for Heller myotomy have been published. Although the robotic approach appears to have some advantages over standard laparoscopy, data on this topic are still controversial and no definite conclusions have been drawn. This metanalysis has been designed to systematically evaluate and compare the effectiveness and safety of the robot-assisted Heller myotomy as compared to the standard laparoscopic approach. According to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, a systematic search on both laparoscopic and robotic Heller myotomy was performed in all the major electronic databases (PubMed, Web of Science, Scopus, EMBASE), using the following search string: (achalasia OR Dor) AND robotic. Six articles were included in the final analysis. A metaregression analysis was performed to assess the possible effects of demographic variables (age, gender, body mass indes (BMI)) and previous abdominal surgery or endoscopic intervention on the analyzed outcomes. No statistical difference was observed in operative times (mean difference (MD) = 20.79, P = 0.19, 95% confidence interval (CI) −10.05,51,62), estimated blood loss (MD = −17.10, P = 0.13, 95% CI −40.48,5.08), conversion rate to open surgery (risk difference (RD) = −0.01, P = 0.33, 95% CI −0.05,0.02), length of hospital stay (MD = −0.73, P = 0.15, 95% CI −1.71,0.25) and long-term recurrence (odds ratio (OR) = 0.59, P = 0.45, 95% CI 0.15,2.33). On the contrary, the robotic approach was found to be associated with a significantly significant lower rate of intraoperative esophageal perforations (OR = 0.13, P < 0.001, 95% CI 0.04, 0.45). Our results suggest that the robotic approach is safer than the laparoscopic Heller myotomy, encouraging the use of robot-assisted surgery. However, our analysis is limited because of the exiguous number of comparative studies and because most of the included studies were statistically underpowered, given the small sample size. Moreover, a high degree of heterogeneity was observed in most of published studies. Taking in consideration the additional costs of robot-assisted procedures, larger Randomized Controlled Trials (RCTs) are advocated to confirm the safety and effectiveness of the robotic approach, and its advantages over standard laparoscopic surgery. In conclusion, well-designed prospective trials and RCTs with homogeneous parameters are needed to draw definitive conclusions about the best surgical approach to pursue in treating symptomatic achalasia.