Advantages of minimally invasive surgery for remnant gastric cancer: A multi-institutional cohort study.

357 Background: Remnant gastric cancer (RGC) is defined as a cancer arising in the remnant stomach after initial gastrectomy, regardless of the previous disease or surgical procedure. Despite growing evidence of the effectiveness of minimally invasive surgery (MIS) for primary gastric cancer, MIS for RGC remains controversial due to the rarity of the disease. This study aimed to evaluate the surgical and oncological outcomes of MIS for radical resection of RGC. Methods: We collected the data of patients with RGC who underwent surgery with curative intent between 2005 and 2020 from 17 institutions in Japan, and performed a propensity score (PS) matching analysis to compare the short- and long-term outcomes of MIS with open surgery. Results: A total of 327 patients were included in this study and 186 patients were analyzed after matching. The risk ratios for overall and severe complications were 0.76 (95% confidence interval [CI]: 0.45–1.27) and 0.65 (95% CI: 0.32–1.29), respectively. The MIS group had significantly less blood loss (50 ml vs. 361 ml, P<0.001) and a shorter hospital stay (13 days vs. 16 days, P=0.009) than the open surgery group, while the operative time was longer in the MIS group (344 min vs. 273 min, P<0.001). The median follow-up duration of this cohort was 4.6 years, and the 3-year overall survival rates were 77.9% in the MIS group and 76.2% in the open surgery group (hazard ratio [HR], 0.78; 95% CI: 0.45–1.36). The 3-year relapse-free survival rates were 71.9% in the MIS group and 62.2% in the open surgery group (HR, 0.71; 95% CI: 0.44–1.16). Locoregional recurrence occurred in three patients (3.2%) in the MIS group and four patients (4.3%) in the open surgery group. There were also no differences in the other patterns of recurrence between the groups. Conclusions: MIS for RGC showed favorable short- and long-term outcomes compared to open surgery. MIS is a promising option for radical surgery for RGC.