Background: We have evaluated the prognostic value of Ki-67 growth fraction after radical prostatectomy, especially focusing on intermediate grade carcinomas.
Materials and methods: 104 patients treated by radical prostatectomy for clinically localized prostate cancer were studied. The area of highest tumour grade was selected from the prostatectomy specimens and used for Ki-67 immunostaining The fraction of Ki-67 positive tumour nuclei in the area of most intense proliferation ("hot spot") was estimated, and related to biochemical failure.
Results: Ki-67 expression (median 6.7%, range 1.2-42.6%) was significantly associated with WHO histological grade. In univariate analysis of all 104 carcinomas, Ki-67 expression was associated with time to biochemical failure as were age, tumour dimension, WHO histological grade, pathological stage, positive surgical margins and pre-operative s-PSA. In multivariate Cox' analysis, Ki-67 expression, pathological stage and pre-operative s-PSA remained as independent predictors of time to biochemical failure. Ki-67 expression (HR 4.8, p < 0.001) was also found to be an independent predictor among moderately-differentiated carcinomas.
Conclusion: Estimates of Ki-67 growth fraction in areas of highest tumour grade may prove to be a useful prognostic biomarker after radical prostatectomy.