Comparison of estimated treatment effects between randomized controlled trials, case-matched, and cohort studies on laparoscopic versus open distal gastrectomy for advanced gastric cancer: a systematic review and meta-analysis

PURPOSE

In actual surgical research, case-matched studies are frequently conducted as an alternative to randomized controlled trials (RCTs). However, it is still unclear what differences there are between RCTs and case-matched studies in upper gastrointestinal surgery, and clarifying them is a very important clinical issue. Thus, the purpose of this study was to investigate estimated treatment effects between RCTs, case-matched studies, and cohort studies regarding laparoscopic distal gastrectomy (LDG) for advanced gastric cancer (AGC).

METHODS

We searched the PubMed, Cochrane Central Register of Controlled Trials, and Web of Science databases for studies that compared LDG versus open distal gastrectomy for AGC published from the inception of the databases until July 2021. A meta-analysis was performed using the Review Manager version 5.3 software program from the Cochrane Collaboration, and six short-term outcomes and three long-term outcomes were assessed.

RESULTS

Twenty-three studies with 13698 patients were included. There was no difference in estimated treatment effects between RCTs and case-matched studies for all outcomes except for the number of retrieved lymph nodes and postoperative complications. In terms of intraoperative blood loss, postoperative hospital stay, number of retrieved lymph nodes, and recurrence, observational studies tended to overestimate the treatment effects.

CONCLUSION

The estimated treatment effects of LDG for AGC in the case-matched study were almost the same as in the RCTs. However, to assess the true magnitude of the treatment effect, the design and actual implementation of the analysis must be critically evaluated.

Laparoscopic versus open distal gastrectomy for advanced gastric cancer: A meta-analysis of randomized controlled trials and high-quality nonrandomized comparative studies

BACKGROUND

Controversy persists about the effects of laparoscopic distal gastrectomy (LDG) versus open distal gastrectomy (ODG) on short-term surgical outcomes and long-term survival within the field of advanced gastric cancer (AGC).

METHODS

Studies published from January 1994 to February 2020 that compare LDG and ODG for AGC were identified. All randomized controlled trials (RCTs) were included. The selection of high-quality nonrandomized comparative studies (NRCTs) was based on a validated tool (Methodological Index for Nonrandomized Studies, MINORS). The short- and long-term outcomes of both procedures were compared.

RESULTS

Overall, 30 studies were included in this meta-analysis, which comprised of 8 RCTs and 22 NRCTs involving 16,029 patients (7864 LDGs, 8165 ODGs). The recurrence, 3-year disease-free survival (DFS), 3-year overall survival (OS), and 5-year OS rates for LDG and ODG were comparable. LDG was associated with a lower postoperative complication rate (OR 0.79; P < 0.00001), lower estimated volume of blood loss (WMD -102.21 mL; P < 0.00001), shorter postoperative hospital stay (WMD -1.96 days; P < 0.0001), shorter time to first flatus (WMD -0.54 day; P = 0.0007) and shorter time to first liquid diet (WMD -0.66 day; P = 0.001). The number of lymph nodes retrieved, mortality, intraoperative complications, intraoperative blood transfusion, and time to ambulation were similar. However, LDG was associated with a longer surgical time (WMD 33.57 min; P < 0.00001).

CONCLUSIONS

LDG with D2 lymphadenectomy is a safe and effective technique for patients with AGC when performed by experienced surgeons at high-volume specialized centers.