Impact of baseline characteristics on extensive‐stage SCLC patients treated with etoposide/carboplatin: A secondary analysis of a phase III study

Background The purpose of the current study is to investigate the impact of baseline characteristics on the outcomes of extensive‐stage small cell lung cancer (SCLC) patients recruited into a clinical trial. Methods This is a secondary analysis of the control arm (etoposide/carboplatin arm) of the ‘NCT00363415’ study which is a phase III study conducted between 2006 and 2007. Univariate analysis of factors affecting overall and progression‐free survival (PFS) was conducted through Cox regression analysis [including age, race, gender, Eastern Cooperative Oncology Group performance score, body mass index, Lactate dehydrogenase, number of metastatic sites and brain metastases]. Factors with P  < .05 in the univariate analysis were then included in the multivariate analysis. Results All patients within the control arm (etoposide/carboplatin) were included in the analysis (N = 455 patients). The following factors were predictive of worse overall survival (OS) in univariate analysis ( P  < .05): performance score = 2, LDH > upper limit of normal and ≥3 metastatic sites. Multivariate Cox regression analysis incorporating these three factors showed that only number of metastatic sites predicts worse OS ( P  < .0001) . Likewise, the following factors were associated with worse PFS in univariate analysis ( P  < .05): performance score = 2 and ≥ 3 metastatic sites predict worse PFS ( P  < .05). Multivariate analysis incorporating these two factors showed that only number of metastatic sites predicts worse PFS ( P  < .0001). Conclusion Number of metastatic sites is the most important predictive factor for overall and PFS among patients with extensive‐stage SCLC treated with systemic chemotherapy within a clinical trial.