In this study, the 4Kscore results from the United States prospective validation study were combined with mpMRI data available from the PROMIS study. The co-authors used likelihood ratios for MRI that detected high-grade disease from PROMIS (positive and negative likelihood ratio of 1.58 and 0.17, respectively) and applied these ratios to probabilities of 4Kscores. Four unique populations were identified based on a threshold for biopsy of 7.5% risk of high-grade disease: (i) men with a very low 4Kscore for whom risk would not be less than 7.5%, even with positive MRI, (ii) men with 4Kscores of less than 7.5% whose risk would be 7.5% or more if the MRI was positive, (iii) men with 4Kscores of 7.5% or higher whose risk would be less than 7.5% if the MRI was negative, and (iv) men with high 4Kscores whose risk would remain 7.5% or greater, even if MRI was negative. In the 4Kscore validation study, 1012 men underwent prostate biopsy, with 23% being diagnosed with Gleason 7 or higher disease. The range of 4Kscores that could be influenced by the results of MRI included 26% of the population with a risk of less than 5% (group 1), 10% with a risk of 5.0%-7.4% (group 2), 45% with a risk of 7.5%-32% (group 3), and 21% with a risk of more than 32% (group 4). Importantly, the net benefit of using 4Kscores alone was 17.7%, mpMRI of 17.6%, and combined strategies of 18.2%.
In summary, this is an sophisticated study combining imaging and biomarkers to further delineate who should or should not undergo a biopsy. Using mpMRI in the setting of low-to-intermediate 4Kscores results in a biopsy strategy with a higher net benefit compared to using either modality alone.
Presented By: Karim Marzouk, MD, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, Toronto, Ontario, Canada
at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA
1. Ahmed HU, El-Shater Bosaily A, Brown LC, et al. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. Lancet. 2017;389:815-822.