Background Glypican-3 (GPC3), a membrane-bound heparan sulphate proteoglycan, may play a role in promoting cancer cell growth and differentiation. Recent studies reported that GPC3 is overexpressed in clear cell carcinoma (CCC) of the ovary, and not other ovarian histotypes. However, in CCC patients, the relationship between the overexpression of GPC3 and prognosis has not yet been clarified.

Aim To evaluate GPC3 expression by immunohistochemistry in CCC.

Methods and Results In 52 CCC patients, GPC3 expression was observed in 40.4%. In cases of CCC, no correlations were identified between GPC3 expression and clinicopathological factors, such as age, FIGO stage, CA125 values, peritoneal cytology, ascitic fluid volume and mortality rate, except for the residual tumour size. GPC3 expression was associated with poor progression-free survival in stage I CCC patients. The numbers of Ki-67-stained cells in GPC3-positive areas were lower than those in GPC3-negative areas. GPC3 expression may be associated with a low proliferation rate in CCC cells. In the early stage of CCC, GPC3-expressing patients tended to be resistant to taxane-based treatment.

Conclusions Results suggest that the overexpression of GPC3 may be related to the low-level proliferation of tumours; it may be associated with resistance to taxane-based chemotherapy and a poor prognosis in CCC of the ovary.