1630PGENOMIC CHARACTERIZATION OF EARLY STAGES OF OVARIAN CANCER WITH EMPHASIS IN LOW-GRADE ENDOMETROID AND LOW-GRADE SEROUS HISTOLOGIES. A STUDY BY SPANISH GROUP FOR OVARIAN CANCER RESEARCH (GEICO)

ABSTRACT Aim: Early-stage (FIGO stage I/IIB) ovarian carcinoma (ESOC) represents 15% of all ovarian cancers and the molecular characterization of their different histologies has not been clearly defined. The aim of this study is to measure genomic abnormalities on a series of ESOCs to identify molecular alterations that influence pathophysiology, prognosis and constitute therapeutic targets. Methods: A centralized pathological review of 573 primary ESOC was performed from samples belonging to the GEICO ESOC Registry. A series of 31 formalin-fixed and paraffin-embedded (FFPE) low-grade endometrioid (LGE) and 15 two-tier low-grade serous (LGS) ESOC were selected for analyses. Recurrence was reported in 6 of the 46 analyzed cases. Transcriptome analyses was performed in 36 cases (12 LGS and 24 LGE) using the GeneChip® Human Transcriptome Array 2.0 (Affymetrix). Whole genome copy number variations (CNV) was analyzed in the 46 cases with the OncoScanTM FFPE Assay Kit (Affymetrix). Results: Expression analyses showed 227 genes differentially expressed (fold change >2.0 and p Conclusions: Our study demonstrates the genomic heterogeneity of LGE and LGS ESOC and provides clues for the identification of potential new biomarkers that could be used as prognostic or therepeutic targets in specific biotypes of ESOC. Disclosure: All authors have declared no conflicts of interest.