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

ABSTRACT

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. IMPLICATIONS FOR PRACTICE With the increasing number of young survivors of gastric cancer (GC), it is essential for clinicians to understand the dynamic prognosis of these patients. Based on large data sets from China and the U.S., this study found that the prognostic factors that predict survival for young patients with GC at baseline vary over time. Although the initial 5-year disease-specific survival is heterogeneous, insight into conditional survival will help clinicians evaluate the long-term prognoses of survivors while ignoring population differences. This knowledge may be more effective in helping young patients with GC to manage future uncertainties, especially when they need to make important life plans.