Topoisomerase II immunostaining as a prognostic marker for survival in ovarian cancer

Objective. This study aimed to evaluate topoisomerase II compared to Ki-67 expression as a marker for tumor behavior and for prognosis of patients with ovarian cancer. Methods. In order to screen for potential prognostic markers, two groups of patients with advanced stage (FIGO stages III and IV) epithelial ovarian carcinoma were selected based on differences in survival (mean survival, 11 years versus 2 years). Pathology slides were reviewed, and immunohistochemistry using antibodies to topoisomerase II and Ki-67 was performed on the original cell blocks. No patients were lost to follow-up. Results. Detectable expression of topoisomerase II was present in 70.0 ± 30.3% of cells in patients with rapidly progressing disease, compared to only 12.3 ± 12.4% of cells in long-term survivors (P = 0.0001). Ki-67 expression was also more frequent in short-term survivors compared to long-term survivors, but the difference was less prominent than with topoisomerase II (P = 0.01). Specificity and sensitivity as prognostic factors reached 88.2 and 93.8% for topoisomerase II, compared to 55.6 and 88.2% for Ki-67. Conclusions. Topoisomerase II expression as detected by immunohistochemistry in tumor samples emerged as a promising clinically relevant biomarker for survival in advanced epithelial ovarian cancer.