Progression-free survival, post-progression survival, and tumor response as surrogate markers for overall survival in patients with extensive small cell lung cancer

ABSTRACT

The effects of first-line chemotherapy on overall survival [OS] might be confounded by subsequent therapies in patients with small cell lung cancer [SCLC]. We examined whether progression-free survival [PFS], post-progression survival [PPS], and tumor response could be valid surrogate endpoints for OS after first-line chemotherapies for patients with extensive SCLC using individual-level data. Between September 2002 and November 2012, we analyzed 49 cases of patients with extensive SCLC who were treated with cisplatin and irinotecan as first-line chemotherapy. The relationships of PFS, PPS, and tumor response with OS were analyzed at the individual level. Spearman rank correlation analysis and linear regression analysis showed that PPS was strongly correlated with OS [r = 0.97, p < 0.05, R[2] = 0.94], PFS was moderately correlated with OS [r = 0.58, p < 0.05, R[2] = 0.24], and tumor shrinkage was weakly correlated with OS [r = 0.37, p < 0.05, R[2] = 0.13]. The best response to second-line treatment, and the number of regimens employed after progression beyond first-line chemotherapy were both significantly associated with PPS [p patients with extensive SCLC. Our findings also suggest that subsequent treatment after disease progression following first-line chemotherapy may greatly influence OS