Objective: To compare the frequency and pattern of E-cadherin expression in endometrioid, papillary serous, and clear cell carcinomas of the endometrium.
Methods: E-cadherin expression was examined in 76 endometrial carcinomas by immunohistochemistry using a monoclonal antibody to E-cadherin and was correlated with poor prognostic indicators such as depth of myometrial invasion, lymph node status, and intraperitoneal spread. The frequency of expression was compared between endometrioid, papillary serous, and clear cell carcinomas by the Fisher exact test. Logistic regression was used to examine the simultaneous effect of histological type and tumor grade on E-cadherin expression.
Results: Sixty-three endometrioid, nine papillary serous, two clear cell, and two carcinomas of mixed histology were examined. E-cadherin negative tumors were more likely to be poorly differentiated (P <.01), have cervical extension (P =.02), have positive peritoneal cytology (P <.01), and have adnexal spread (P =.01) when compared with E-cadherin positive tumors. Papillary serous and clear cell carcinomas were significantly less likely to express E-cadherin than endometrioid carcinoma (38% versus 95%, P <.001). Tumor grade and histological type were identified as significant predictors of E-cadherin expression in univariable analysis; however, only histological type remained significant in multivariable analysis (P =.01). When grade was controlled, endometrioid carcinoma remained 23 times more likely to express E-cadherin than papillary serous and clear cell carcinomas.
Conclusion: Papillary serous and clear cell carcinomas are significantly less likely to express E-cadherin than endometrioid tumors. This difference may account for the more aggressive behavior of papillary serous and clear cell carcinomas.