Clinical impact of post-progression survival for overall survival in patients with limited-stage disease small cell lung cancer after first-line chemoradiotherapy
Objectives: The effects of first-line chemoradiotherapy on overall survival (OS) may be confounded by subsequent lines of therapy in patients with limited-stage disease small cell lung cancer (LD-SCLC). Therefore, we aimed to determine the relationships between progression-free survival (PFS) or post-progression survival (PPS) and OS after first-line chemoradiotherapy in LD-SCLC.
Methods: We retrospectively analyzed 71 LD-SCLC patients who received first-line chemoradiotherapy and had disease recurrence between September 2002 and March 2013 at Shizuoka Cancer Center (Shizuoka, Japan). We determined the correlation between PFS and OS between PPS and OS at the individual level. In addition, we performed univariate and multivariate analyses to identify significant prognostic factors of PPS.
Results: OS is more strongly correlated with PPS (Spearman's r=0.86, R2=0.72, p<0.05) than PFS (Spearman's r=0.46, R2=0.38, p<0.05). In addition, the response to second-line treatments, the presence of distant metastases at recurrence and the number of additional regimens after first-line chemoradiotherapy were significant independent prognostic factors for PPS.
Conclusions: PPS has more impact for OS than PFS in LD-SCLC patients. Moreover, treatments administered after first-line chemoradiotherapy may affect their OS. However, larger multicenter studies are needed to validate these conclusions.