Spatial expression of the FGFR2b splice isoform and its prognostic significance in endometrioid endometrial carcinoma

Patient demographic, clinicopathologic and survival outcome data and tissue samples were obtained from women at different menstrual periods with apparent normal endometrium, women with hyperplasia and endometrial cancer. Samples are collected from Mater Hospital (Brisbane, Australia), Tissue microarray samples from US Biomax and 460 samples from Vancouver achieved cohort samples collected for genomic profiling by the Canadian group. All samples were assessed for Fibroblast Growth Factor Receptor 2 isoforms (FGFR2b and FGFR2c mRNA) using a novel BaseScope RNA in situ hybridisation assay developed by our laboratory. The FGFR2 protein in the samples was assessed using immunohistochemistry. Using the FGFR2b and FGFR2c mRNA pattern of expression, we categorised endometrial cancer into four categories. The FGFR2b and FGFR2c mRNA expression were associated with the clinicopathologic profiles and clinical outcomes. We found exclusive FGFR2b isoform expression on the epithelial compartment of normal endometrium and hyperplasia without atypia and FGFR2b expression was associated with longer progression-free survival and disease-specific survival.