Characteristics and clinical outcomes of patients with nonsmoking small cell lung cancer in Korea

Abstract

BackgroundThe aim of this study was to investigate the characteristics and clinical outcomes of patients with nonsmoking small cell lung cancer (SCLC) using a nationwide registry in Korea.MethodsThe Korean Association for Lung Cancer developed a registry in cooperation with the Korean Central Cancer Registry (KCCR) and surveyed approximately 10% of recorded lung cancer cases.ResultsFrom 2014 to 2016, the KCCR registered 1,043 patients newly diagnosed with SCLC among a total of 8,110 lung cancer patients. In subgroup analysis, Kaplan meier survival analysis showed that the overall survival (OS) was significantly shorter in the nonsmoking subgroup than the ever-smoking subgroup of SCLC patients with extensive disease (6.99 vs. 9.68 months; P = 0.016). Among SCLC patients with limited disease, OS was also shorter in the nonsmoking subgroup, without statistical significance (19.4 vs. 23.5 months; P = 0.247). In a multivariate analysis using a Cox regression model, never smoking was not associated with shorter OS, but older age, extensive stage, poor performance status (Eastern Cooperative Oncology Group grade ≥ 2), male sex, no prophylactic cranial irradiation, and no active treatment (chemotherapy and/or radiotherapy) were associated with poor prognosis.ConclusionThis evaluation of an unbiased nationwide survey dataset revealed that a significant proportion of Korean SCLC patients were never-smokers. No history of smoking appeared to be a significant prognostic factor according to the univariate analysis but was confirmed to be statistically insignificant through a multivariate analysis of the total population. Reasons for a poor prognosis may include the possibility that a high rate of the elderly population is composed of nonsmokers who did not receive active treatment.