Prognosis of Young Survivors of Gastric Cancer in China and the U.S.: Determining Long-Term Outcomes Based on Conditional Survival

Background Young survivors of gastric cancer (GC) have better prognoses than elderly patients, yet their disease-specific survival (DSS) has received little attention. Patients and Methods Data on young patients (aged ≤40 years) with GC undergoing resections at three Chinese institutions (n = 542) and from the SEER database (n = 533) were retrospectively analyzed. Three-year conditional disease-specific survival (CS3) was assessed. The effects of well-known prognostic factors over time were analyzed by time-dependent Cox regression. Results Overall, young Chinese patients with GC had a better 5-year DSS than U.S. patients (62.8% vs. 54.1%; p < .05). The disease-specific mortality likelihood of the entire cohort was not constant over time, with most deaths occurring during the first 3 years after surgery but peaking at 1 and 2 years in China and the U.S., respectively. Based on 5-year survivorship, the CS3 rates of both groups were similar (90.9% [U.S.] vs. 91.5% [China]; p > .05). Cox regression showed that for Chinese patients, site, size, T stage, and N stage were independent prognostic factors at baseline (p < .05). For U.S. patients, grade, T stage. and N stage significantly affected DSS at baseline (p < .05). In both groups, only T stage continuously affected DSS within 3 years after gastrectomy. However, for both groups, the initial well-known prognostic factors lost prognostic significance after 5 years of survival (all p > .05). Although the 5-year DSS rates of young Chinese patients with T3 and T4a disease were significantly better than those of young U.S. patients, in each T stage, the CS3 of both regions trended toward consistency over time. Conclusion For young patients with GC, the factors that predict survival at baseline vary over time. Although the initial 5-year DSS is heterogeneous, insight into conditional survival will help clinicians evaluate the long-term prognoses of survivors while ignoring population differences.