FGF18 as a potential biomarker in serous and mucinous ovarian tumors

Fibroblast growth factor 18 (FGF18) has been suggested to play important roles in promoting progression of ovarian high-grade serous carcinoma. Our aim was to investigate FGF18 expression in the whole spectrum of serous and mucinous ovarian tumors, highlighting differences in expression within the adenoma-carcinoma sequence and differences between type I and type II tumors. We also aimed to test the prognostic significance of this expression and its relation to microvessel density (MVD). We evaluated the immunohistochemical expression of FGF18 and CD31 in 103 ovarian tumors and statistically analyzed their association with clinicopathological variables and patients' outcome. FGF18 score increased significantly within the adenoma-carcinoma sequence for serous and mucinous tumors. MVD increased significantly only among serous tumors. FGF18 and MVD correlated significantly (overall and among serous tumors only) and were significantly higher in type II than type I tumors. Cox regression models were built. Independent predictors could not be determined due to multicollinearity between the predictors. However, the combination of International Federation of Gynecology and Obstetrics (FIGO) stage, ovarian carcinoma type, and/or FGF18 score achieved the highest predictability of poor prognosis. FGF18 could play a role within the adenoma-carcinoma sequence in type I tumors and might modulate angiogenesis among serous tumors. Our findings further augment the differences between type I and type II tumors. The combination of FIGO stage, ovarian carcinoma type, and/or FGF18 score could predict poor prognosis among ovarian carcinoma patients. Our work identifies FGF18 in ovarian neoplasia as a promising field of research, although evaluation of the performance of the developed models is still needed.