Disappearance of steroid hormone dependency during malignant transformation of ovarian clear cell cancer.

Ovarian clear-cell carcinoma (OCCA) and ovarian endometrioid carcinoma (OEMC) are often associated with endometriosis. This study determined the immunohistochemical expression of steroid hormone receptors and cancer-related genes in OCCA and OEMC specimens containing endometriosis and atypical endometriosis. Pathological progression from endometriosis to atypical endometriosis to carcinoma was identified in 4 of 22 OCCAs and 4 of 16 OEMCs. Using paraffin-embedded tissue samples, expression and changes in expression for estrogen receptors (ERs) and progesterone receptors (PRs) were examined in relation to the observed pathological changes. A gradual reduction in ERalpha and PRA expression was observed with malignant transformation from endometriosis to atypical endometriosis to OCCA. In OEMC, ERalpha expression increased with malignant transformation. In conclusion, reductions in ERalpha and PRA expression were observed with progression from endometriosis to atypical endometriosis in OCCA specimens. Disappearance of hormone dependency might therefore be associated with malignant transformation to OCCA.