Steroid sulfatase expression in ovarian clear cell adenocarcinoma: immunohistochemical study

OBJECTIVE: Steroid sulfatase (STS) is an important enzyme that converts biological inactive steroid sulfate to active free steroid. As estrogen is thought to play an important role in cell proliferation in gynecological cancer, the existence of STS may have particular significance in the prognosis of ovarian cancer. In the present study, we determined the STS expression of ovarian clear cell adenocarcinoma (OCCA), which has the poorest prognosis among various ovarian cancers, immunohistochemically to clarify the biological nature of OCCA and also to determine whether STS expression is one of the prognostic factors in OCCA. METHODS: Forty-five archival, formalin-fixed, paraffin-embedded tissues from patients with OCCA and other epithelial ovarian cancers who were first operated on from 1987 to 1998 were subjected to analysis. Twenty-eight of forty-five (60.9%) OCCA cases coexisted with endometriosis. They were subclassified into papillary, solid, and tubulocystic types with respect to architectural pattern. Immunohistochemical staining of STS was performed using anti-human STS polyclonal rabbit antibody that had been immunized with purified STS from human placenta. RESULTS: STS was immunohistochemically stained positively in 70% (32/45) of OCCA, 33.3% of serous adenocarcinoma (6/18), and 50.0% of mucinous adenocarcinoma (4/8) specimens and was localized in the cytoplasm of neoplastic epithelial cells. No significant relationship was found between STS staining and FIGO staging. However, patients diagnosed as papillary type had a significantly lower survival rate and showed significantly more positive staining of STS (P < 0.05) than those with solid type. Stage, STS expression, and architectural type yielded a significant association with survival rate. CONCLUSION: It was proven that STS is present in the cytoplasm of patients with OCCA by an immunohistochemical method. OCCA patients with papillary tumor with positive STS expression are considered to have a poor prognosis.