Conditional survival of patients with gastric cancer who undergo curative resection: A multi-institutional analysis in China.

BACKGROUND: Conditional survival estimates, which take into consideration the changing risk with increasing survival time, provide a dynamic survival probability and more accurate survival information for clinician decision making. The objective of the current study was to evaluate the conditional disease-specific survival (DSS) for patients with gastric cancer who underwent curative surgery in China.

METHODS: In total, 7658 patients with gastric cancer from a multi-institutional cohort in China were included in the analyses. Actuarial DSS was estimated using the Kaplan-Meier method. Three-year conditional DSS (CDS3 ) of patients who had already survived for x years was estimated as CDS3 = DSS(x + 3)/DSS(x). Cox proportional hazards regression analyses were used to identify the factors related to DSS.

RESULTS: The 1-year, 3-year, and 5-year actuarial DSS rates were 88.2%, 64.5%, and 54.6%, respectively. By using CDS estimates, the probabilities that patients would remain alive for an additional 3 years given that they had already survived for 1, 3, and 5 years were 66.6%, 80.2%, and 88.3%, respectively. Patients who had unfavorable tumor characteristics diagnosed initially at surgery had the greatest improvement in CDS and the largest survival gap between actuarial DSS and CDS.

CONCLUSIONS: The current results indicate that CDS estimates for Chinese patients with gastric cancer who underwent surgery were dynamic and increased with time elapsed. Patients who had unfavorable tumor characteristics had the greatest improvement in CDS. This valuable information could provide more a precise evaluation of long-term prognosis and may serve as an important prognostic index in clinical practice. Cancer 2018;124:916-24. © 2017 American Cancer Society.