Clinical validity of proliferating cell nuclear antigen as an objective marker for evaluating biologic features in patients with untreated prostate cancer

Background:  Although Gleason grading may be the most useful system for evaluating biological activity of untreated prostate cancer, lack of interobserver validity with Gleason scores (GS) is an unsolved issue. In this study, the proliferating cell nuclear antigen labeling index (PCNA LI) in untreated prostate cancer was investigated in order to clarify the usefulness of supplemental and objective markers for evaluating the biologic features of prostate cancer. Methods:  Sixty cases of prostate cancer were randomly selected from the cancer registry in Gunma University Hospital for this study. PCNA LI were evaluated using paraffin-embedded biopsy cores taken at diagnosis. Correlation of PCNA LI with the Gleason grading system, clinical stage, serum prostate-specific antigen (PSA) levels and age were evaluated. Cumulative rates of freedom from cause-specific death were also evaluated stratified by various clinicopathologic features, including PCNA LI using Kaplan–Meier analysis. Results:  Proliferating cell nuclear antigen labeling index was significantly higher in patients with PSA levels over 100 ng/mL, advanced clinical stage (>T4, N1 or M1 disease), higher Gleason grade or with a higher GS than in those with other clinicopathologic features. The 5-year cumulative rate of death from prostate cancer was significantly higher at 62% in patients with a PCNA LI of 20 or more than those with PCNA LI of less than 20, who accounted for 4%. Conclusions:  Proliferating cell nuclear antigen labeling index in combination with Gleason grading system may be of clinical value in evaluating biologic features and also in predicting cause specific survival of prostate cancer in an objective, reliable and reproducible manner.