Risk and Prognosis of Subsequent Primary Gastric Cancer

Introduction: The incidence and prognostic impact of subsequent primary gastric cancer (GC) in a population of other cancer survivors is unclear. We aimed to evaluate susceptibility to subsequent primary GC in cancer survivors and prognosis of GC with prior cancer history. Methods: A total of 2,211 and 23,416 GC cases with and without prior cancer history were retrospectively selected from the Surveillance, Epidemiology, and End Results (SEER) database. Potential risk of developing subsequent primary GC was assessed through standardized incidence ratios (SIRs). Cox regression was adopted to analyze the influence of prior cancer history and clinical characteristic factors on the prognosis of subsequent primary GC. A nomogram was established to predict overall survival (OS). Propensity score matching was conducted to eliminate possible bias. Results: Compared with general population, cancer survivors had an increased risk of subsequent primary GC (SIR 1.17, 95% CI: 1.15–1.20, p < 0.05). Prior cancer history was related to poor OS of GC (adjusted hazard ratio [aHR] 1.12, 95% CI: 1.06–1.19, p < 0.001), but not cancer-specific survival (aHR 0.97, 95% CI: 0.89–1.05, p = 0.441). In addition, age, grade, stage, year of diagnosis, surgery, TNM stage, and tumor size were independent prognostic factors for OS in GC cases with prior cancers. The concordance index of the nomogram was 0.72 (95% CI: 0.71–0.74), and calibrate curves showed good agreement between prediction by the nomogram and actual observation. Conclusions: Cancer survivors with increased risk of developing subsequent primary GC should strengthen their monitoring and follow-up to prevent occurrence of subsequent primary GC.