Prognostic impact of cigarette smoking on the survival of patients with established nasopharyngeal carcinoma.

BACKGROUND: Cigarette smoking is associated with the etiology of nasopharyngeal carcinoma; however, the influence of smoking on survival in patients with established nasopharyngeal carcinoma remains unknown. METHODS: We retrospectively analyzed 1,849 patients with nasopharyngeal carcinoma who were categorized as never, former, and current smokers. Cumulative effect of smoking was defined in terms of pack-years. Associations between cigarette exposure and survival were estimated by Cox proportional hazards model. RESULTS: The risks of death, progression, locoregional relapse, and distant metastasis were significantly higher for former and current smokers (all P </= 0.002) than never smokers. Heavy smokers with high pack-years had HRs for death of 3.31 [95% confidence interval (CI), 2.58-4.26; P < 0.001], for progression of 2.53 (95% CI, 2.03-3.16; P < 0.001), and for distant metastasis of 2.65 (95% CI, 1.89-3.70; P < 0.001). Specifically, in the cohort of 495 patients treated with intensity-modulated radiotherapy/three-dimensional conformal radiotherapy, we obtained similarly significant results. All of the survival outcomes remained significant in multivariate analyses. CONCLUSIONS: Pretreatment cigarette smoking is an independent, poor prognostic factor for patients with nasopharyngeal carcinoma, which is associated with increased risk of death, progression, locoregional relapse, and distant metastasis, with the risk increasing with pack-years. IMPACT: It is clear that cigarette smoking not only promotes carcinogenesis in the normal nasopharyngeal epithelium, but also affects the survival of patients with nasopharyngeal carcinoma.