Survival Outcomes For De Novo Versus Relapsed Stage Iv Gastric And Gastroesophageal Junction (Gej) Adenocarcinoma.

148Background: In gastric/GEJ cancer, 40% of patients (pts) are metastatic at diagnosis (de novo stage IV) and up to 70% with locoregional disease recur (relapsed stage IV). We compared survival outcomes between de novo vs relapsed stage IV. Methods: A retrospective observational study of stage IV gastric/GEJ pts was conducted (2012-2015). Overall survival (OS) was from date of stage IV diagnosis. PFS1 defined the period from stage IV diagnosis to first progression. PFS2 was from first to second progression. For relapsed stage IV pts, disease-free interval (DFI) was the period from initial diagnosis to metastatic relapse. Cox proportional hazards models compared OS, PFS1 and PFS2 between de novo vs relapsed stage IV pts, stratified by DFI [ 12 months (mo)] and controlled for baseline patient characteristics. Results: Of 198 pts, 62% were male and median age was 64 years (26-93), with 64% gastric and 36% GEJ adenocarcinomas. Primary therapy for locoregional pts included surgery (75%), perio...