Non-small cell lung cancer in never smokers: a clinical entity to be identified

OBJECTIVES: It has been recognized that patients with non-small cell lung cancer who are lifelong never-smokers constitute a distinct clinical entity. The aim of this study was to assess clinical risk factors for survival among never-smokers with non-small cell lung cancer. METHODS: All consecutive non-small cell lung cancer patients diagnosed (n = 285) between May 2005 and May 2009 were included. The clinical characteristics of never-smokers and ever-smokers (former and current) were compared using chi-squared or Student's t tests. Survival curves were calculated using the Kaplan-Meier method, and log-rank tests were used for survival comparisons. A Cox proportional hazards regression analysis was evaluated by adjusting for age (continuous variable), gender (female vs. male), smoking status (never- vs. ever-smoker), the Karnofsky Performance Status Scale (continuous variable), histological type (adenocarcinoma vs. non-adenocarcinoma), AJCC staging (early vs. advanced staging), and treatment (chemotherapy and/or radiotherapy vs. the best treatment support). RESULTS: Of the 285 non-small cell lung cancer patients, 56 patients were never-smokers. Univariate analyses indicated that the never-smoker patients were more likely to be female (68% vs. 32%) and have adenocarcinoma (70% vs. 51%). Overall median survival was 15.7 months (95% CI: 13.2 to 18.2). The never-smoker patients had a better survival rate than their counterpart, the ever-smokers. Never-smoker status, higher Karnofsky Performance Status, early staging, and treatment were independent and favorable prognostic factors for survival after adjusting for age, gender, and adenocarcinoma in multivariate analysis. CONCLUSIONS: Epidemiological differences exist between never- and ever-smokers with lung cancer. Overall survival among never-smokers was found to be higher and independent of gender and histological type.