Smoking status as a prognostic factor in patients with stage I pulmonary adenocarcinoma

Background. Cigarette smoking is a well-known risk factor for lung carcinogenesis; however, its effect on tumor progression is still unclear. We herein investigated the influence of cigarette smoking on postoperative prognosis in patients with non-small cell lung cancer (NSCLC). Methods. The postoperative survival and pathologic stage of 999 patients with NSCLC who underwent a curative resection were retrospectively investigated in relation to the pack-year index (PYI). Results. Adenocarcinoma patients with a PYI of less than 20 showed a more favorable prognosis than those with a PYI of 20 or more, whereas no difference was observed among the subgroups of squamous cell carcinoma patients. In adenocarcinoma, stage I disease was a significantly larger population in never-smokers than in smokers. A multivariate analysis revealed that the smoking habit (yes or no) and stage (IA or IB), but not gender or histologic subtype (bronchioloalveolar type or not), are independent prognostic factors in stage I adenocarcinoma with hazard ratios of 1.8 and 2.3, respectively. Conclusions. The smoking status is a significant prognostic factor for stage I pulmonary adenocarcinoma.