Impact of progression type on overall survival in patients with advanced gastric cancer based on randomized phase III study of S-1 plus oxaliplatin versus S-1 plus cisplatin

Abstract

The association between progression type and survival has been reported in breast cancer, but remains unclear in advanced gastric cancer (AGC). Here, this association was assessed using data obtained from an earlier randomized phase III study demonstrating the non-inferiority of S-1 plus oxaliplatin (SOX) to S-1 plus cisplatin (CS) on progression-free survival and overall survival (OS) in the first-line treatment of AGC. A Cox regression model including two time-dependent covariates, progression with new lesions and with no new lesions, was used to determine their effect on OS in each treatment group. When both types of progression were detected simultaneously, this was categorized as progression with new lesions. Progression with and with no new lesions was identified in 91 and 167 patients, respectively, in the SOX group (333 patients) and 95 and 147 patients, respectively, in the CS group (330 patients). The association between progression type and OS was similar in both treatment groups; both progression types were strong poor prognostic factors, particularly progression with new lesions [hazard ratio (HR), 7.26; 95% confidence interval (CI), 4.89-10.80 in SOX and HR, 5.78; 95% CI, 4.13-8.08 in CS] compared to no new lesions (HR, 4.66; 95% CI, 3.21-6.77 in SOX and HR, 2.71; 95% CI, 1.95-3.75 in CS). Progression accompanied by new lesions had a strong negative impact on OS in patients treated with S-1 and platinum for AGC.