Prognostic value of the new international association for the study of lung cancer/American thoracic society/European respiratory society lung adenocarcinoma classification on death and recurrence in completely resected stage i lung adenocarcinoma

OBJECTIVE:: This study investigated the prognostic value of the new International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) lung adenocarcinoma classification in resected stage I lung adenocarcinoma. METHODS:: Histological classification of 283 patients undergoing surgical resection for stage I lung adenocarcinoma was determined according to the IASLC/ATS/ERS classification after comprehensive histological subtyping with recording of the percentage of each histological component (lepidic, acinar, papillary, micropapillary, and solid) in 5% increments. Their impact on overall survival, recurrence, and postrecurrence survival was investigated. RESULTS:: The 5-year overall survival and recurrence-free rates were 81.6% and 76.9%, respectively. During follow-up, 57 (20.1%) patients developed recurrence. The 2-year postrecurrence survival rate was 72.3%. The solid predominant group is associated with significant more male sex, higher smoking exposure, larger tumor size, and more poorly differentiated histological grade. Lepidic predominant group had significantly better overall survival (P = 0.002). Micropapillary and solid predominant groups had significantly lower probability of freedom from recurrence (P = 0.004). Older age (P = 0.039), visceral pleural invasion to the surface (PL2) (P = 0.009), and high grade (micropapillary/solid predominant) of the new classification (P = 0.028) were predictors of recurrence in multivariate analysis. The solid predominant group tends to have significantly worse postrecurrence survival (P = 0.074). CONCLUSIONS:: The new adenocarcinoma classification has significant impact on death and recurrence in stage I lung adenocarcinoma. Patients with PL2 and micropapillary/solid predominant pattern have significant higher risk for recurrence. This information is important for patient stratification for aggressive adjuvant chemoradiation therapy.