Hyperthermic intraperitoneal chemotherapy (HIPEC) for gastric cancer with peritoneal metastasis - Joint analysis of European GASTRODATA and American national cancer database

Introduction: Palliative chemotherapy is the current standard among advanced gastric cancer (GC) patients with peritoneal metastasis (PM), while the role of gastrectomy with cytoreductive surgery and HIPEC remains unclear. The current study aimed to assess treatment outcomes among GC patients with PM undergoing gastrectomy and hyperthermic intraperitoneal chemotherapy (HIPEC) using multinational cancer registries. Methods: The analysis (2012-2022) included stage IV GC patients with PM undergoing gastrectomy and HIPEC from the European GASTRODATA Registry (EU cohort) and the American National Cancer Database (NCDB, U.S. cohort). The study outcomes were textbook oncological outcome (TOO) assessment and overall survival (OS). Results: Among 193 patients, 49.7 % were from the EU cohort and 50.3 % from the U.S. cohort. EU cohort had significantly higher rates of pT4 tumors (EU: 50 % vs U.S.: 40.2 %), metastatic lymph nodes (EU: 68.8 % vs U.S.: 54.6 %), and >16 lymph nodes evaluated (EU: 91.7 % vs U.S.: 68%). Postoperatively, the EU cohort had longer hospital stay (EU: 53.1 % vs 22.2 %, p < 0.001), with no significant differences in 30-day readmission (EU: 14.6% vs U.S: 7.2%, p = 0.11) and 90-day mortality (EU: 4.2 % vs U.S.: 9.3%, p = 0.25). TOO rates were 30.2 % and 32 % for EU and U.S. cohorts, respectively. Within the U.S. cohort, TOO achievement was associated with improved 1- (86.7% vs. 57.4 %), 3- (55.8 % vs. 29.7 %), and 5-year OS (50.2 % vs. 29.7%) (p = 0.0025) survival compared with non-TOO. Conclusions: Among patients with GC and PM undergoing gastrectomy and HIPEC, achievement of TOO was associated with decreased risk of postoperative complications (EU cohort) and improved long-term survival (U.S.