Association between smoking during radiotherapy and prognosis in head and neck cancer: a follow-up study.

Background: The study objective was to confirm a previous finding that patients with stage III/IV squamous head and neck cancer (SHNC) who smoke during radiotherapy (RT) experience reduced survival.

Methods: An observational cohort study. Patients' smoking status was assessed weekly by questionnaire plus blood cotinine. Patients were assessed every 3 to 4 months for survival. Logistic regression and Cox proportional hazards analyses were used to detect the independent contribution of smoking on survival.

Results: Of 148 patients, 113 smoked during RT. Blood cotinine and smoking questionnaire responses were highly correlated (Spearman R = .69; p < .0005). Abstainers and very light smokers experienced better survival than light, moderate, and heavy smokers (median, 42 vs 29 months; p = .07). Tumor and nodal status and years smoked were the most important prognostic factors. Smoking during RT was not an independent predictor of survival, but baseline smoking status was (p = .016).

Conclusion: Smoking status should be documented in all future trials of RT in SHNC to allow for pooled analyses with sufficient power to address this question.