hK2 and Free PSA, a Prognostic Combination in Predicting Minimal Prostate Cancer in Screen-Detected Men within the PSA Range 4-10 ng/ml

Objectives: The purpose of screening for prostate cancer is to decrease the disease-specific mortality. However not every screen-detected prostate cancer is a threat to the patient's life. The risk of overdetection and subsequent overtreatment in prostate cancer has been recognised. The purpose of this investigation was to evaluate the role of tumour markers total PSA, free PSA, and hK2, and their combinations in predicting minimal prostate cancer. Methods: Within the European Randomized Study of Screening for Prostate Cancer (ERSPC), section Rotterdam, The Netherlands, prebiopsy serum samples were analysed for 100 selected men who underwent a radical prostatectomy for their screen-detected prostate cancer. All had a PSA value between 4 and 10 ng/ml prior to diagnosis. Minimal prostate cancer is defined as organ confined, Gleason score ≤6 (no Gleason grade 4 or 5), and tumour volume <0.5 ml. Results: Sera and tumour volumes from 91 men were available for analysis. Minimal prostate cancer was diagnosed in 16.5% of the selected cases. Mean tumour volume was 1.2 ml (range: 0.04-13.5); hK2, the algorithms hK2/fPSA, and hK2/%fPSA have significant correlations with tumour volume. Both algorithms also yielded the best test results in predicting minimal disease with an area under the receiver operator characteristics curve of 82%. Conclusions: hK2 and percent free PSA have added prognostic value for the detection of minimal prostate cancer in screen-detected cases within PSA range 4-10 ng/ml. These biomarkers can possibly be used to select less invasive treatment options like active surveillance and to prevent overtreatment.

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