Clinical and molecular differences between clear cell and papillary serous ovarian carcinoma.

Purpose: The aim of the current study is to compare clear cell ovarian carcinoma (CCOC) and papillary serous ovarian carcinoma (PSOC) with respect to their clinical features and expression of different regulators of cell cycle, apoptosis, and chemoresistance.

Experimental Design: Women with stage III CCOC (n = 9) and those with stage III, poorly differentiated PSOC (n = 21) seen between 1996 and 2000 and treated with cytoreductive surgery followed by paclitaxel and platinum chemotherapy were compared in their demographic features, tumor marker profile, surgical substage, results of cytoreductive surgery, thromboembolic complications, response to chemotherapy, and tumor recurrence. Tumor samples were compared in their expression of p53, Bcl(2), Bcl(x), Bax, p21, p-glycoprotein (PGP), multi-drug resistance-associated protein (MRP), lung resistance protein (LRP), and glutathione S-transferase (GST) using immunohistochemistry.

Results: Women with CCOC had significantly lower mean preoperative CA-125 values, lower surgical substage, less expression of p53, and more expression of p21 than women with PSOC (P = 0.037, 0.012, 0.008, and 0.009, respectively). Women with CCOC had less ascites, smaller amount of residual tumor, higher incidence of thromboembolism, chemoresistance, more expression of Bcl(2), and less expression of PGP than women with PSOC (P = 0.067, 0.078, 0.108, 0.114, 0.091, and 0.118, respectively).

Conclusions: Women with CCOC exhibit certain clinical and molecular differences compared to stage- and grade-matched women with PSOC. Women with CCOC have a smaller tumor volume and manifest different expressions of p53, p21, and Bcl(2) than women with PSOC. Although further studies with larger number of patients are needed, our findings indicate that chemoresistance in CCOC is probably not p53-dependent.