Short-Term Outcomes from a Randomized Screening Phase II Non-inferiority Trial Comparing Omentectomy and Omentum Preservation for Locally Advanced Gastric Cancer: the TOP-G Trial

Background Omentectomy is considered an essential part of curative gastrectomy for locally advanced gastric cancer (GC), albeit without solid evidence. We conducted a randomized phase II trial (the TOP-G trial) comparing omentectomy and omentum preservation for gastric cancer. This report describes the short-term findings regarding the trial’s secondary endpoints. Methods The trial protocol was submitted to the University Hospital Medical Information Network Clinical Trials Registry ( http://www.umin.ac.jp/ctr/ : UMIN000005421). The key eligibility criteria were histologically confirmed cT2–4a and N0–2 gastric adenocarcinoma. Short-term surgical outcomes, including morbidity and mortality, were compared between the omentectomy group (group A, control arm) and the omentum-preserving surgery group (group B, test arm). All procedures were performed via an open approach. Based on a non-inferiority margin of 7%, statistical power of 0.7, and type I error of 0.2, the sample size was set to 250 patients. Results A total of 251 patients were eligible and randomized (group A: 125 patients, group B: 126 patients) between April 2011 and October 2018. After excluding patients who had peritoneal metastasis or laparotomy history, safety outcomes were analyzed for 247 patients. Group A had a significantly longer median operation time (225 min vs. 204 min, p = 0.022) and tended to have greater median blood loss (260 mL vs. 210 mL p = 0.073). The incidences of morbidity were similar and < 10% in both groups (8% vs. 9%, p = 1.000). There was no mortality in either group. Conclusions Operative risk was generally similar between omentectomy and omentum-preserving surgery for locally advanced gastric cancer.