Survival and pretreatment prognostic factors for extensive‐stage small cell lung cancer: A comprehensive analysis of 358 patients

Background Extensive‐stage small cell lung cancer (ES‐SCLC) is deemed as a fatal malignancy with a poor prognosis. Although immunotherapy has gradually played an important role in the treatment of ES‐SCLC since 2018, ES‐SCLC treatment data and patient outcome before 2018, when chemotherapy served as a fundamental therapeutic strategy, is still meaningful as a summary of the situation regarding previous medical treatment and is a baseline for comparative data. In addition, the prognostic factors of ES‐SCLC have failed to reach a consensus until now. Therefore, this study aimed to evaluate survival and identify the prognostic factors in an ES‐SCLC population. Methods We retrospectively collected the detailed medical records of 358 patients with ES‐SCLC from January 1, 2011 to December 31, 2018 in a Chinese top‐level cancer hospital. The prognostic factors were evaluated by Cox univariate and multivariate analysis. Results The median overall survival (OS) of ES‐SCLC patients (N = 358) was 14.0 months, the one‐ and two‐year OS rates were 56.2% and 21.7%, respectively. Moreover, we identified two demographic characters (age ≥ 70, smoking index ≥ 400), one tumor burden factor (bone multimetastasis), two tumor biomarkers (cyfra211, CA125) and two laboratory indexes (decreased Na, PLR