Significance of Smoking as a Postoperative Prognostic Factor in Patients with Non-small Cell Lung Cancer

IntroductionIn this study, we investigated the influence of smoking on the postoperative prognosis in patients with non-small cell lung cancer.MethodsThe subjects consisted of 770 patients who underwent a resection of lung cancer in our department between 1994 and 2005. We compared the clinico-pathological findings between the smoking and never-smoking groups. The pack-year index (PYI) was used as a smoking index.ResultsThe smoking group consisted of 569 patients (74%), and the never-smoking group consisted of 201 patients (26%). The smokers were composed of 492 men and 77 women. Among the adenocarcinoma patients, there were 293 (61%) smokers and 185 (39%) never-smokers. The patients with squamous cell carcinoma included 204 (95%) smokers and 10 (5%) never-smokers. The proportion of patients with stage IA disease was significantly higher in the never-smokers than that of the smokers. The 5-year survival rate after surgery was 66% in the never-smoking group; however, the rates were 56% in patients with a PYI more than or equal to 20, and 55% in those with PYI more than 20. Seventy-nine (13.9%) patients in the smoking group and seven (3.5%) patients in the never-smoking group died of other diseases, with a significant difference (p < 0.01). Of these patients, 44 (56%) and 13 (16%) in the smoking group died of respiratory and cardiovascular disorders, respectively. In our series, excluding those who died of other diseases, there were no significant differences in the postoperative prognosis.ConclusionsIn the smoking group, the prognosis was poorer than that in the never-smoking group. The higher proportion of early stage disease (stage IA) and female gender were major causes of the better prognosis of the never-smokers. Nevertheless, the high pulmonary/cardiovascular complication-related mortality was another cause of the poor prognosis of the smokers with lung cancer.