Gastric remnant cancer and long-term survival in Central Norway 2001 to 2016 - A population-based study.

Introduction: Gastric remnant cancer (GRC) has been defined as a distinct clinical entity and is reported to account for 1-8% of all gastric cancers. We aimed to characterize GRC patients and assess survival in a Western population.

Methods: Retrospective population-based cohort study including 1217 patients diagnosed with gastric adenocarcinoma in Central Norway 2001-2016. GRCs (n = 78) defined as adenocarcinomas arising in the residual stomach after distal gastrectomy were compared to non-GRC (n = 1139) and to proximal non-GRC (n = 595).

Results: 78 (6.4 %) gastric cancers were GRC. The annual number and proportion of GRC declined during the study period (p = 0.003). Median latency from distal gastrectomy to GRC diagnosis was 37.6 years (15.7-68.0) and previous Billroth II reconstruction was most common (87.7%). Compared to controls, GRC patients were more frequently males (83.3%), diagnosed in earlier TNM stages and were older at diagnosis. A smaller proportion of GRC patients received perioperative or palliative chemotherapy, but the R0/R1resection rate of 41.0% was no different from non-GRC patients. Overall median survival for GRC patients irrespective of treatment was 7.0 months, which did not differ from non-GRCs or proximal non-GRC. In multivariate analyses TNM stage and age were independently associated with mortality, whereas GRC per se was not.

Conclusions: Numbers of GRCs declined during the study period, but the latency between distal gastrectomy and GRC diagnosis was long. GRC patients were more frequently male and older than other gastric cancer patients. GRC was not independently associated with survival after adjusting for TNM stage and tumor location.