Prognostic value of smoking status in operated non-small cell lung cancer

Abstract

Despite the indisputable link between smoking and the increased risk for lung cancer, the inclusion of this factor in prognostic survival analysis has been scarce. Important clinical questions regarding the smoking status are the basis of this study and are as follow: what is the prognostic benefit of having been a non-smoker or having stopped smoking prior to developing lung cancer and what is the prognostic benefit of smoking cessation at the time of diagnosis of lung cancer? Cigarette smoking status of 311 patients operated for non-small cell lung cancer (NSCLC) by a single surgeon was determined based on two independent questionnaires taken prospectively prior to lung operation. Of all patients analysed, 169 (54.3%) were current smokers, 25 (8.0%) were non-smokers, 82 (26.4%) were former smokers and 35 (11.3%) were recent quitters. A Cox multiple regression model was used to test the prognostic value of smoking status on survival together with other relevant clinicopathological factors. For overall survival, older age (P = 0.011), presence of lymph node metastases (P < 0.001) and current smoking (P = 0.001) were independent predictors of poor prognosis, while non-smokers (relative risk = 0.447, 95% confidence interval = 0.206-0.970, P = 0.042), former smokers (relative risk = 0.543, 95% confidence interval = 0.350-0.843, P = 0.006) and recent quitters (relative risk = 0.340, 95% confidence interval = 0.164-0.705, P = 0.004) had a significant better prognosis compared to current smokers (referent group). Similar results were obtained for disease-free survival. These results indicate that smoking cessation is beneficial for lung cancer patients at any time point prior to lung operation and current smoking at the time of operation is associated with poor prognosis.