Clinicopathological Significance of Early-Stage Lung Adenocarcinoma with Micropapillary Component: Associations with Prognosis, EGFR and KRAS Gene Mutations
Akihiko Yoshizawa, Shinji Sumiyoshi. Shinshu University Hospital, Matsumoto, Nagano, Japan; Kyoto University Hospital, Kyoto, Japan
Background: Lung adenocarcinoma with micropapillary component (LA-MPC) is known to have biologically aggressive behavior and its predominant tumor was listed up as a new entity of invasive adenocarcinoma by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. The aim of this study was to evaluate the clinicopathological characteristics of early-stage LA-MPC and to investigate correlations between LA-MPC and the EGFR or, KRAS mutation status.
Design: We retrospectively reviewed 440 LA patients who underwent resection. We defined LA-MPC as adenocarcinoma with MPC occupying at least 5% of the entire tumor. EGFR and KRAS mutations were detected using the established methods.
Results: Of 440 cases, 256 cases were classified as Stage IA cases. Of which, 53 cases (20.7%) had MPC. The disease-free 5-year survival rates of the MPC-negative and MPC-positive groups in stage IA tumors were 92.1% and 77.6%, respectively, and there was statistically significant difference between the groups (p = 0.003). On the other hand, the overall 5-year survival rates of the MPC-negative and MPC-positive groups in stage IA tumors were 91.8% and 92.3%, respectively, showing no statistically significant difference (p = 0.973). Recurrent rates of LA-MPC were significantly higher (n = 10, 17.8%) than cases without MPC (4.4%) (p < 0.001). No KRAS mutation was detected in all the ten cases. Of the six alive cases with disease, EGFR mutations were detected in 5 cases (83.3 %) and the four of them were treated with a tyrosine kinase inhibitor (TKI) with long survival (median: 64.6 months). Additionally, one case with EGFR mutation was detected in four dead cases, who died 100.6 months later after initial resection with using TKI.
Conclusions: LA-MPC, defined as occupying 5% or more of the entire tumor, was associated with a strongly invasive nature and was a prognostic factor in early-stage patients. Moreover LA-MPCs were biologically aggressive but could be controlled by EGFR-TKIs.
Monday, March 4, 2013 1:00 PM
Poster Session II # 290, Monday Afternoon