Immunohistochemical study of proliferating cell nuclear antigen (PCNA) in epithelial ovarian tumors

We used an immunohistochemical technique to determine whether monoclonal antibody (PC 10) for proliferating cell nclear antigen (PCNA) could be useful as a marker of proliferating cells with formalin-fixed, paraffin-embedded tissue sections of 116 epithelial ovarian tumors. The mean labeling rate for PCNA was 33.0% in the malignant group (79 cases), 12.5% in the borderline-malignant group (17 cases) and 3.4% in the benign group (20 cases), showing significant differences among all groups. The mean labeling rate for PCNA in the malignant group was significantly higher, 35.0%, in the prechemotherapy group (61 cases) than in the postchemotherapy group (18 cases: 26.1%). These results suggest that the decrease in proliferating activity in the malignant cases with PCNA staining may be attributable to chemotherapy. Furthermore, there was a positive correlation (r=0.57) between the labeling rate for PCNA and mitotic activity. These results suggest that PCNA is a useful marker for distinguishing malignant tumors and assessing mitotic activity.