Clinical impact of post-progression survival on overall survival in elderly patients with extensive disease small-cell lung cancer

Abstract

Background: The effects of first-line chemotherapy on overall survival (OS) might be confounded by subsequent therapies in patients with small-cell lung cancer (SCLC). Therefore, the objective of our study was to determine the relationships between progression-free survival (PFS) or post-progression survival (PPS) and OS after first-line chemotherapy in elderly patients with extensive disease-SCLC (ED-SCLC), using individual level data. Methods: Between July 1998 and December 2014, we analyzed 57 cases of elderly patients with ED-SCLC who were treated with carboplatin and etoposide as first-line chemotherapy. The relationships between PFS and PPS with OS were analyzed at an individual level. Results: Spearman rank correlation and linear regression analyses showed that PPS was strongly correlated with OS (r = 0.92, P < 0.05, R 2 = 0.83) and PFS was moderately correlated with OS (r = 0.76, P < 0.05, R 2 = 0.25). The best response at second-line treatment and the number of regimens after progression beyond first-line chemotherapy were both significantly associated with PPS (P < 0.05). Conclusions: PPS has a stronger impact on OS than PFS in elderly ED-SCLC patients after first-line chemotherapy. In addition, the response at second-line treatment and the number of additional regimens after first-line treatment are significant independent prognostic factors for PPS. These results suggest that OS in elderly ED-SCLC patients may be influenced by treatments subsequent to first-line chemotherapy; however, this remains to be verified with prospective studies.