Background: Loss of E-cadherin represents a hallmark of plasmacytoid differentiation. We analyzed the effect of membranous E-cadherin loss and its nuclear accumulation in patients with locally advanced conventional urothelial carcinoma (UC) who were treated with radical cystectomy and adjuvant chemotherapy.
Methods: A total of 247 formalin-fixed, paraffin-embedded tumor samples were reviewed to detect histological variants of UC. Immunohistochemical staining of E-cadherin was performed and analyzed for membranous and nuclear expression. The correlation between E-cadherin expression and histology was assessed, and overall survival (OS) was analyzed with univariate and multivariate Cox regression and Kaplan-Meier analyses. Correlation of nuclear E-cadherin to tumor stage (pT), lymph node metastasis (pN), histologic subtype, and chemotherapy was performed by Fisher's exact test.
Results: Membranous and nuclear E-cadherin expression was strongly correlated to plasmacytoid urothelial carcinoma (PUC) (p < 0.001). Complete loss of membranous E-cadherin expression was observed in 76.2 % of PUCs, 11.1 % of conventional UCs, and 0 % of micropapillary urothelial carcinoma (MPCs). Nuclear accumulation was found in 47.6 % of PUCs, 10 % of MPCs, and 1.8 % of UCs. Sixty-two percent of all tumors with negative membranous E-cadherin expression and nuclear accumulation were PUCs (p = 0.035). In a Kaplan-Meier analysis, mean survival with nuclear E-cadherin expression was 31.9 months [95 % confidence interval (CI) 16.1-47.6] of patients without nuclear staining 61 months (95 % CI 53.5-67.7; p = 0.045). A univariate Cox regression analysis showed that nuclear E-cadherin accumulation was associated with a 2-fold increase in risk of death (95 % CI 1.03-4.06; p = 0.04). In multivariate Cox regression analysis adjusted to type of chemotherapy, tumor stage, and tumor grade, the hazard ratio for patients with nuclear E-cadherin was 2.03 (95 % CI 1.00-4.121; p = 0.050).
Conclusions: Nuclear E-cadherin is associated with PUCs and is suggested to be an independent prognostic factor in advanced UC.