Abstract In 2016, Kaiser Permanente Northern California regionalized gastric cancer care, introducing a regional comprehensive multidisciplinary care team, standardizing staging and chemotherapy, and implementing laparoscopic gastrectomy and D2 lymphadenectomy for patients eligible for curative-intent surgery. This study evaluated the effect of regionalization on outcomes. The retrospective cohort study included gastric cancer cases diagnosed from January 2010 to May 2018.