Abstract 591: Prognostic implications of PI3K mutation and amplification in curatively resected liposarcoma

Abstract

Abstract Background: We investigated the epidemiologic characteristics and prognostic significance of PIK3CA mutation/amplification in curative resected liposarcoma. Methods: A total of 125 liposarcoma tissue samples were collected over a 12-year period (2000-2012). PIK3CA mutation and amplification of gene copy number were analyzed by pyrosequencing method and fluorescence in situ hybridization (FISH). Results: Nine of the 105 liposarcoma patients (8.6%) showed activating PIK3CA mutation.PIK3CA mutations were more frequent in myxoid/round cell and pleomorphic type vs well differentiated/dedifferentiated type (11.1% vs 88.9%, P = 0.044). In FISH analysis of PIK3CA, amplification of PIK3CA was detected in 31 of the 102 patients (30.4%) and histologic differences was not statistically significant in patients with PIK3CA amplification (48.4% vs 51.6%, p = 0.328). In survival analysis, PIK3CA amplified patients showed worse prognosis compared with PIK3CA-non amplified patients (median disease free survival (DFS) 119.2 vs 38.3 months p = 0.01). In multivariate analysis, positive PI3KCA amplification was an independent worse prognostic factor for DFS (p = 0.04; HR, 2.6; 95% CI 1.36 to 5.1). PIK3CA mutation was not associated with significant difference for DFS (p = 0.739) Conclusion: We demonstrated that histologic differences according to PIK3CA mutation or amplification status. PIK3CA amplification was an independent worse prognostic factor for DFS. Further studies are needed to evaluate the potential diagnostic and therapeutic role of PIK3CA mutation and amplification in liposarcoma. Citation Format: Joo Hoon Kim, Hyo Song Kim, Jae Seok Lee, Ki Hyang Kim, Yong Jin Cho, Kyu Hyun Park, Soo Hee Kim, Joong Bae Ahn, Woo Ik Yang, Young Han Lee, Jin-Suck Suh, Kyoo-Ho Shin, Sun Young Rha. Prognostic implications of PI3K mutation and amplification in curatively resected liposarcoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 591. doi:10.1158/1538-7445.AM2015-591