Background: The purpose of this study was to examine the association between cigarette smoking and histological subtypes of lung adenocarcinoma. Methods: We reviewed a total of 320 consecutive patients with stage I adenocarcinoma who underwent complete resections with systematic node dissections from January 2004 to December 2006 at the National Cancer Center Hospital East. Results: A statistically significant difference was observed in recurrence-free probabilities between never smokers and ever smokers (3-year recurrence-free probabilities of 95.6% and 88.6%, respectively, p = 0.034). Among adenocarcinoma histological subtypes, only a solid component was significantly more frequent in ever smokers than in never smokers (p < 0.001). Among patients with solid components, significantly more cases had lymphatic permeation (p = 0.007), intratumoral vascular invasion (p < 0.001), and visceral pleural invasion (p < 0.001). Multivariate analysis revealed that ever-smoking history was the only statistically significant independent clinical predictor for a solid component (p < 0.001). Among ever smokers, smoking extent in pack-years of patients with solid components was significantly greater than that of those without solid components (p < 0.001). With respect to predominant subtypes, smoking extent in pack-years of patients with predominantly solid adenocarcinomas was significantly greater than that of patients with predominantly bronchioloalveolar carcinoma, papillary, or acinar adenocarcinomas (all p < 0.001). Conclusion: A greater smoking extent was associated with the presence of adenocarcinoma solid components, which may have more aggressive biological features resulting in poorer outcomes.
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