Pack‐years of cigarette smoking as a prognostic factor in patients with stage IIIB/IV nonsmall cell lung cancer

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Abstract
BACKGROUND: This study was undertaken to characterize the relation between the survival of patients with stage IIIB/IV nonsmall cell lung cancer (NSCLC) and pack‐years of cigarette smoking (graded according to the American Joint Committee on Cancer staging system).METHODS: Data were analyzed from patients with stage IIIB/IV NSCLC who had completed a prospective smoking questionnaire. The impact of pack‐years of cigarette smoking, age, sex, Karnofsky performance status (KPS), and the presence of weight loss >5% was evaluated on overall survival using univariate and multivariate analyses.RESULTS: Smoking history and clinical data were available for 2010 patients with stage IIIB/IV NSCLC (1004 women and 1006 men). Approximately 70% of patients (1409 patients) had smoked >15 pack‐years, 13% (270) were former and current smokers who had smoked ≤15 pack‐years, and 16% (331) were never‐smokers (P < .001). Among smokers, patients with a ≤15 pack‐year history of smoking had a longer median survival than patients who had smoked >15 pack‐years (14.6 months vs 10.8 months; log‒rank P = .03). As the number of pack‐years increased, the median overall survival decreased (log‒rank P < .001). Multivariate analysis indicated that a history of smoking was an independent prognostic factor (hazard ratio, 1.36; P < .001).CONCLUSIONS: More cigarette smoking, measured in pack‐years, was associated with decreased survival after a diagnosis of stage IIIB/IV NSCLC. Trials assessing survival in patients with stage IIIB/IV NSCLC should report a detailed cigarette smoking history for all patients. Cancer 2010. © 2009 American Cancer Society.