Nuclear β‐catenin and CDX2 expression in ovarian endometrioid carcinoma identify patients with favourable outcome

Aims Ovarian endometrioid carcinoma (EC) generally has a good prognosis. Adjuvant chemotherapy can be spared in low‐stage disease, but prognostic biomarkers are needed to refine the treatment threshold. Wnt/β‐catenin signalling is commonly altered in EC. We examined immunohistochemical expression of nuclear β‐catenin and CDX2 as prognostic biomarkers for EC; both are mediators of the Wnt pathway. Methods and results We evaluated two ovarian EC cohorts, discovery set (n = 183) and validation set (n = 174), with ovarian cancer‐specific survival (OCSS) as the primary end‐point. In univariable analysis, nuclear β‐catenin expression was significantly associated with longer OCSS in the discovery set [hazard ratio (HR) = 0.36, 95% confidence interval (CI) = 0.16–0.74, P = 0.004] and the validation set (HR = 0.35, 95% CI = 0.11–0.89, P = 0.006). Similar significant associations were observed with CDX2 expression in the discovery set (HR = 0.25, 95% CI = 0.11–0.50, P