Abstract
BackgroundWe investigated the epidemiologic characteristics and prognostic significance of PIK3CA mutations/amplifications in curative resected liposarcoma.Patients and methodsA total of 125 liposarcoma tissue samples were collected over a 12-year period. PIK3CA mutations and gene copy number amplifications were analyzed by pyrosequencing and fluorescence in situ hybridization (FISH).ResultsNine of the 105 liposarcomas (8.6%) had activating PIK3CA mutation. PIK3CA mutations were more frequent in myxoid/round cell and pleomorphic tumors compared with well-differentiated/dedifferentiated tumors (13.3% vs. 2.2%, P=0.043). In FISH PIK3CA analysis, copy number gain was detected in 14 of the 101 tumors (13.9%): 11 (10.9%) tumors had increased gene copy number (polysomy) and 3 (3.0%) exhibited gene amplification. In survival analysis, patients with PIK3CA copy number gain had a worse prognosis compared to patients without PIK3CA amplification (median disease-free survival [DFS] 22.2 vs. 107.6 months p=0.005). By multivariate analysis, PIK3CA copy number gain was an independent prognostic factor for worse DFS (P=0.027; hazard ratio, 2.400; 95% confidence interval 1.105 to 5.213). PIK3CA mutation was not associated with DFS and overall survival.ConclusionsWe demonstrated PIK3CA mutation and amplification in liposarcoma. PIK3CA copy number gain was an independent poor prognostic factor for DFS. Further studies are needed to evaluate the potential diagnostic and therapeutic role of PIK3CA mutations and amplifications in liposarcoma.
Highlights
Soft tissue sarcoma (STS) is a heterogeneous disease with over 50 histologic subtypes, with various biological behaviors and genetic features [1]
Surgical resection is the primary treatment for localized disease, many liposarcomas eventually progress to advanced disease that is either unresectable, metastatic, or both
We evaluated the frequency of PIK3CA amplification and mutation in surgically resected liposarcoma
Summary
Soft tissue sarcoma (STS) is a heterogeneous disease with over 50 histologic subtypes, with various biological behaviors and genetic features [1]. Surgical resection is the primary treatment for localized disease, many liposarcomas eventually progress to advanced disease that is either unresectable, metastatic, or both. For patients with those tumors, the mortality is high, and local and/or systemic tumor burden results in significant morbidity [3]. Liposarcoma is subdivided into 5 subtypes by the World Health Organization classification: well-differentiated, myxoid/round cell, dedifferentiated, pleomorphic, and mixed-type liposarcoma [4]. Well-differentiated and myxoid liposarcoma are low-grade tumors, while dedifferentiated, round cell, and pleomorphic liposarcoma are high-grade tumors. We investigated the epidemiologic characteristics and prognostic significance of PIK3CA mutations/amplifications in curative resected liposarcoma
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