Objective:To analyse the relationship between endometriosis and endometrioid adenocarcinoma of the ovary

and investigate the expression of ER

PR and pS2 proteins in endometrioid adenocarcinoma tissue. Methods: 63 cases of endometrioid adenocarcinoma of the ovary were observed retrospectively under the light microscope

and immunohistochemical staining for ER

PR and pS2 were performd in the tumor tissues. Results: Among the 63 cases

there were 8(12.7%)accompanied with endometriosis

of which 1 was observed having transitional lesions ranging from the benign endometriosis to malignant endometrioid carcinoma.Of the 63 cases

Admixtures of endometrioid carcinoma with mucinous were present in 3 cases

and with serous carcinoma in 2.Positive expression rates for ER

PR and pS2 protein in endometrioid carcinoma were 38.1%(24/63)

46.2%(26/63) and 25.4% (16/63)

respectively.There was an apparent correlation between the expressions of ER and pS2 protein ( P <0.01).Conclusion: Endometrioid carcinoma of the ovary originates mainly from the coelomic epithelium of the ovary

and few cases arise from the malignant transformation of endometriosis.The hormones must have some role in the development and growth of the carcinomas.The detection of ER

PR

and pS2 may be helpful in instructing hormone manipulation therapy to endometrioid carcinoma.