Does Ki-67 staining improve quantitative histology in preoperative prostate cancer staging?

To evaluate accuracy of Ki-67 expression on biopsy specimens in comparison with quantitative histology findings for preoperative prostate cancer (PCa) staging. From January 2008 to January 2010, 126 patients (median age 63 years) underwent radical retropubic prostatectomy; median PSA was 9.1 ng/mL; 98 and 28 patients had a clinical stage T1c and T2, respectively. The following variables of quantitative histology were evaluated as predictive of non organ-confined (OC) PCa: Gleason score > 6, TPC > 20%, GPC > 50%, cancer-positive cores > 2, presence of cancer-positive cores in both lateral margins and bilateral PCa. Value of Ki-67% staining in all cancerous cores was calculated. Sixty (47.7%) patients had a non OC-PCa with positive nodes in 12 (20%) cases. The mean Ki-67 score was 4.4%: 3.7% in OC-PCa and 5.6% in non-OC-PCa, respectively. Predictive positive value (PPV) of quantitative histology, Ki-67 (cut-off > 5%) and both parameters to predict a non-OC-PCa vs an OC-PCa was equal to 90%, 40% and 93.4%, vs 36.6%, 78.8% and 78.8%, respectively. Ki-67 staining on biopsy specimens does not improve quantitative histology in predicting non-OC-PCa; moreover, the low expression of Ki-67, even in presence of advanced disease, decreases its prognostic value in predicting an OC-PCa.