Validation of the IASLC/ATS/ERS Lung Adenocarcinoma (ADC) Classification and Use of Comprehensive Histologic Subtyping (CHS) for Architectural Grading in 432 Japanese Patients.
Akihiko Yoshizawa, Shinji Sumiyoshi, Andre L Moreira, William D Travis. Kyoto University Hospital, Japan; Memorial Sloan-Kettering Cancer Center, New York
Background: A new lung adenocarcinoma (ADC) classification is being proposed by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS) and European Respiratory Society (ERS). Moreover we have reported how CHS proposed in the new classification can be used for architectural grading system of early stage resected lung ADC. The purpose of this study is to validate the proposed histological classification and the histological grading system of lung ADC in Japanese patients (pts).
Design: 432 lung ADC pts who had undergone resection in Kyoto University hospital from 2001 to 2009 were retrospectively reviewed. Comprehensive histologic subtyping was used to estimate the percentage of each histologic subtype and to identify the predominant subtype. Tumors were classified according to the new ADC classification with predominant subtypes for overtly invasive tumors and our proposal histological grading system [Grade1: composed of ADC in situ (AIS), minimally invasive ADC (MIA), lepidic ADC (LP), Grade2: composed of papillary ADC (PP) and acinar ADC (AP), Grade3: composed of solid ADC (SP) and micropapillary ADC (MP)]. Survival analysis was performed using Kaplan Meier method.
Results: There were 206 females (48%) and 226 males (52%) with a median age of 65.5 years (23-88 years) and 250 Stage 1A pts, 88 Stage 1B pts, 30 Stage 2A pts, 13 Stage2B pts, 26 Stage3A pts, 4 Stage3B pts and 15 Stage4 pts. 5-yr disease free survival (DFS) rates of the group classified by the new classification were shown below: 100% for AIS (n=17) and MIA (n=35), 88.8% for LP (n=33), 67% for PP (n=180), 59% for AP (n=56), 61% for SP (n=71), 17% for MP (n=19). Moreover 5-yr DFS for mucinous ADC (n=15) and others (n=6, including colloid ADC) were 79.5% and 44.4%, respectively. The 5-yr DFS for patient with Grade1 was significantly better than Grade2 and Grade3 (90%, 65% and 51%, respectively (p<0.001).
Conclusions: The new classification of lung ADC identifies histologic categories with prognostic differences that may be helpful in identifying candidates for adjunctive therapy. AISs and MIAs had 100% 5-year survival confirming previous report. In contrast mucinous carcinomas appear to have worst prognosis. Moreover the new histological grading system could be used to select patients with higher risk of recurrence and to provide valuable information for clinicians to manage postsurgical therapy.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 273, Tuesday Afternoon