Abstract: ObjectiveTo study the expression of Yesassociated protein(YAP) in endometrial cancer and its clinical pathological significance. MethodsImmunohistochemical MaxVisionTM method was used to detect the expression of YAP in 289 cases of endometrial cancer, and its relationship with clinical pathological features and prognosis were analyzed. ResultsThe expression rate of YAP in type Ⅱ endometrial cancer was higher than that in typeⅠendometrial cancer (87.0% vs. 55.1%, χ2=16.340, P＜0.001). In typeⅠendometrial cancer, the expression rate of YAP in G1 cases was lower than that in G2G3 cases (51.6% vs. 80.0%, χ2=8.549, P=0.005), not associated with menopausal status （χ2=0.045， P=0.831）, FIGO stage （χ2=0.976， P=0.323）, lymph vascular space invasion （χ2=0.000， P=1.000）, lymph node metastasis （χ2=0.976， P=0.323） and ER status （χ2=3.318， P=0.069）. In typeⅡendometrial cancer, the expression of YAP was not significantly associated with menopausal status （χ2=0.305， P=0.581）, FIGO stage （χ2=2.395， P=0.122）, lymph vascular space invasion （χ2=1.441， P=0.230）, lymph node metastasis （χ2=1.351， P=0.245） and ER status （χ2=0.000， P=1.000）. Logrank test analysis showed that YAP highexpression was associated with a significantly worse overall survival in typeⅠ endometrial cancer  （χ2=14.023,  P＜0.001）, but YAP expression was not an independent prognostic factor. ConclusionYAP shows high expression in endometrial cancer. It is associated with histological grade and prognosis of typeⅠ endometrial cancer.

Key words: Endometrial neoplasms, Prognosis, Immunohistochemistry, Yesassociated protein