Molecular Alterations of PIK3CA in Uterine Carcinosarcoma, Clear Cell, and Serous Tumors

Objectives: Type II endometrial carcinomas-uterine carcinosarcomas or uterine malignant mesodermal mixed tumors (UMMMTs), clear cell carcinomas (UCCs), and uterine serous carcinomas (USCs)-are aggressive malignancies that present with advanced disease and have high mortality rates. PIK3CA mutations are commonly found in endometrial cancers. The objective of the study was to characterize molecular alterations in the PIK3CA gene in these tumors. Methods: A total of 84 cases (20 UMMMTs, 18 UCCs, and 46 USCs) were selected from the surgical pathology files of Weill Cornell Medical College and Johns Hopkins Hospital. The diagnoses were confirmed by gynecologic pathologists (L.H.E. and A.Y.). DNA was extracted from paraffin-embedded tissue. Polymerase chain reaction was performed for mutational analysis. All the studies were performed in accordance with approved Institutional Review Board protocols. Results: Mutations in the PIK3CA gene were identified in 3 (15%) of 20 UMMMT, 3 (16.7%) of 18 UCC, and 10 (21.7%) of 46 USC cases. We report novel mutations in PIK3CA in uterine carcinosarcoma. Conclusions: A significant percentage of UMMMTs, UCCs, and USCs have mutations in PIK3CA. Further investigation is needed to develop targeted therapies for these aggressive uterine cancers.