CTNNB1 Mutations and Aberrant β-Catenin Expression in Ovarian Endometrioid Carcinoma: Correlation With Patient Outcome.

CTNNB1 mutations and aberrant β-catenin expression have adverse prognosis in endometrial endometrioid carcinoma, and recent evidence suggests a prognostic role of β-catenin in ovarian endometrioid carcinoma. Thus, we aimed to determine the prognostic value of the CTNNB1 mutational status, and its correlation with β-catenin expression, in a well-annotated cohort of 51 ovarian endometrioid carcinomas. We performed immunohistochemistry for β-catenin and developed an 11-gene next-generation sequencing panel that included whole exome sequencing of CTNNB1 and TP53. Results were correlated with clinicopathologic variables including disease-free and disease-specific survival. Tumor recurrence was documented in 14 patients (27%), and cancer-related death in 8 patients (16%). CTNNB1 mutations were found in 22 cases (43%), and nuclear β-catenin in 26 cases (51%). CTNNB1 mutation highly correlated with nuclear β-catenin (P<0.05). Mutated CTNNB1 status was statistically associated with better disease-free survival (P=0.04, log-rank test) and approached significance for better disease-specific survival (P=0.07). It also correlated with earlier International Federation of Gynecology and Obstetrics stage (P<0.05). Nuclear β-catenin, TP53 mutations, age, ProMisE group, surface involvement, tumor grade and stage also correlated with disease-free survival. There was no association between membranous β-catenin expression and disease-free or disease-specific survival. CTNNB1 mutations and nuclear β-catenin expression are associated with better progression-free survival in patients with OEC. This relationship may be in part due to a trend of CTNNB1-mutated tumors to present at early stage. β-catenin immunohistochemistry may serve as a prognostic biomarker and a surrogate for CTNN1B mutations in the evaluation of patients with ovarian endometrioid neoplasia, particularly those in reproductive-age or found incidentally without upfront staging surgery.