Correlation between overall survival and other endpoints in clinical trials of second-line chemotherapy for patients with advanced gastric cancer

Abstract

Background: The correlation between progression-free survival (PFS) or time to progression (TTP) and overall survival (OS) has been evaluated in patients with advanced gastric cancer (AGC) who received first-line chemotherapy. No corresponding analysis has been done in patients who have undergone second-line chemotherapy.

Methods: We evaluated the correlation between PFS, TTP, objective response rate (ORR), disease control rate (DCR), and OS in patients with AGC who underwent second-line chemotherapy. Correlations were evaluated by Spearman rank correlation coefficient (ρ).

Results: Sixty-four trials, including 10 randomized studies, were selected for analysis. Median PFS/TTP moderately correlated with OS (ρ = 0.56). The correlation tended to be stronger in non-Asian trials (ρ = 0.74) than in Asian trials (ρ = 0.37). ORR and DCR did not strongly correlate with OS (ρ = 0.38 for ORR; ρ = 0.54 for DCR). The hazard ratio of PFS and OS in each of the arms of the 10 randomized studies also showed a low correlation (ρ = 0.36).

Conclusions: PFS/TTP, ORR, and DCR did not correlate sufficiently with OS to be used as surrogate endpoints in patients with AGC who have undergone second-line chemotherapy. Further research is needed based on individual patient data from ongoing randomized trials.