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

ABSTRACT

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 neversmokers 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 percent vs. 32 percent) and have adenocarcinoma (70 percent vs. 51 percent). Overall median survival was 15.7 months (95 percent 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.