Surgical results of non-small cell lung cancer in never-smokers as a separate entity

Abstract

7505 Background: Recent information about epidermal growth factor receptor gene mutations suggests that there are two etiologically different forms of lung cancer based on the smoking status. In order to propose ‘never-smoking non-small cell lung cancer (NSLC)‘ as a separate entity, the clinico-pathologic differences of operable NSLC between never smoking patients and patients with a history of smoking were investigated. Methods: The medical records of 1405 patients with primary NSLC who underwent a complete resection at our institution from 1974 through 2004 were reviewed for the clinico-pathologic variables and postoperative survival. Results: The proportion of never-smoking patients with NSLC has been significantly increasing over 30 years from 15.9% in the 1970's to 32.8% in the 2000's. A significantly greater proportion of female patients or adenocarcinoma patients was found in the ‘never-smoking NSLC‘ group in comparison to the ‘smoking NSLC’ group (85.8% vs. 11.2%; 87.8% vs. 49.1%, respectively). The distribution of the pathologic T status was significantly different between the never-smoking NSLC group and the smoking NSLC group (more T1 patients in the never-smoking NSLC group), although that of the pathologic N status was not different. In both the overall and cancer-specific survivals, the ‘never-smoking NSLC’ patient group was significantly superior to the ‘smoking NSLC’ group. In addition to the smoking status, the factors significantly associated with the postoperative survival rate were gender, histologic type, T-status and N-status by the univariate analyses. A multivariate analysis revealed the never-smoking status to be an independent prognostic factor, besides a pathologic T and N status. Conclusions: From now on, ‘never-smoking NSLC’ should therefore be both clinically and basically investigated as a distinct entity from ‘smoking-associated NSLC’. No significant financial relationships to disclose.