Abstract
199 Background: Disease-free survival after adjuvant chemotherapy in colon and gastric cancer has already been validated as a surrogate endpoint for OS. However, there have been no reports evaluating PFS as a surrogate endpoint in resectable EC. Standard treatment for resectable EC is preoperative chemotherapy (preCx) or chemoradiotherapy (preCRT) followed by surgery. This study was conducted to evaluate the trial level correlations between PFS and OS in resectable EC with PreTx and to explore potential merit of PFS as a surrogate endpoint for OS. Methods: A systematic literature search of randomized trials with preCx or preCRT for EC reported from January 1990 to September 2014 was conducted using PubMed and the Cochrane library. Weighted linear regression using sample size of each trial as a weight was used to estimate coefficient of determination (R2) within PFS and OS. 95% confidence interval of R2 was estimated by bootstrap method. The primary analysis included trials in which the HR of PFS and OS were reported. A sensitivity analysis included trials in which either HR or median survival time of PFS and OS was reported. In the sensitivity analysis, HR was estimated from the median survival time of PFS and OS, assuming exponential distribution. Results: Of 615 articles, 9 trials (2,725 patients) were selected for the primary analysis and 12 (3,020) for the sensitivity analysis. Median numbers of enrolled patients were 256 (range 101-802) in primary analysis, and 209 (75-802) in sensitivity analysis. The numbers of trials including only preCx, only preCRT and both, were 5, 4 and 0 in the primary analysis, and 5, 6 and 1 in the sensitivity analysis. The primary analysis did not show the correlation between treatment effects on PFS and OS (R2 0.217, 95%CI [0.003-0.910]). The sensitivity analysis did not show the association of PFS and OS (R2 0.153, 95%CI [0.000-0.682]). Conclusions: Although the number of randomized controlled trials evaluating PreTx for EC is limited at the moment, PFS was not suitable as a surrogate endpoint for OS. OS should be used as the primary endpoint in trials of PreTx for resectable EC.
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