P-166PROGNOSTIC VALUE OF THE IASLC/ATS/ERS CLASSIFICATION OF LUNG ADENOCARCINOMA IN RESECTED STAGE I DISEASE IN PURE CAUCASIAN PATIENTS

Objectives: To investigate the prognostic value of the International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary lung adenocarcinoma classification in stage I resected Caucasian patients. Methods: We identified 146 consecutive patients with pathological stage I lung adenocarcinoma submitted to lobectomy and mediastinal lymph nodes dissection between 2006 and 2010. No patients had preoperative treatments. Histological subtypes were classified according to the IASLC/ATS/ERS lung adenocarcinoma classification. Patient's 5-year overall survival (OS) and disease-free survival (DFS) were calculated. Survival was assessed on December 2013. Results: Among 146 patients, 1 minimally invasive adenocarcinoma (MIA) (0.6%), and 145 invasive adenocarcinoma (IVA) (99.4%) were detected; IVA were 6 lepidic predominant (4%), 57 acinar predominant (39%), 39 papillary predominant (26%), 37 solid predominant (25%), 5 micropapillary predominant (3%), 2 invasive mucinous (1.5%) subtype, respectively. Mean follow-up was 46 months (range 6-79).The 5-year DFS and OS for the entire series were 64% and 75%, respectively. According to the histological subtypes the 5-year DFS and OS were 100% and 100% for MIA and lepidic, 77% and 88% for acinar, 63% and 77% for papillary, 48% and 55% for solid and 28% and 43% for micropapillary and invasive mucinous adenocarcinoma, respectively. Significant differences were recorded when histological subtype survivals were compared (P < 0.05). Conclusions: MIA and lepidic predominant represent a limited proportion of adenocarcinoma subtypes in Caucasian patients (5%), whereas 30% of the cases are constituted by highly aggressive subtypes as solid, micropapillary and invasive mucinous adenocarcinoma. The different histological subtypes significantly correlate with the long-term outcome. The constitution of lung adenocarcinoma series in terms of tumour subtypes should be kept in mind when comparing results of lung cancer treatment from different populations. Disclosure: No significant relationships.