Distinct molecular profiles for histological subtypes of epithelial ovarian adenocarcinomas

Background: It has been shown that based on gene expression profiles, subgroups within epithelial ovarian cancers (EOC) can be identified. We studied a well characterized series of ovarian carcinomas from patients treated at our institute using gene expression profiling to better define clinically significant subgroups. Methods: Gene expression profiling was performed using RNA of 90 primary fresh frozen EOC samples representing all histological subtypes and stages (FIGO I-IV). Patients underwent either primary or interval debulking surgery and if indicated taxane-based chemotherapy. Pathology was reviewed for all cased and complete follow-up, including treatment response and recurrences was available for all patients. Results: Unsupervised and supervised analysis of gene expression data showed distinct subtypes correlating with histology. Mucinous carcinoma was the most distinct subtype based on gene expression profile. No significant differences in gene expression profile between high and low grade serous carcinomas could be observed. No gene expression signatures associated with survival or treatment response could be identified. Conclusion: Histological subtypes of ovarian adenocarcinomas are characterized by distinct gene expression profiles. In order to find signatures correlated to outcome of treatment it is essential that gene expression profiling studies are performed in histological homogeneous groups. 90 fresh frozen EOC samples representing all histological subtypes (53 high grade serous, 8 low grade serous, 14 undifferentiated, 6 mucinous, 6 enodometrioid en 3 clear cell carcinomas) and all FIGO stages (10 I-IIA and 80 IIB-IV)