PD17-01: Derivation and external validation of a RAPID Risk score for predicting clinically significant prostate cancer in men with an MRI visible lesion: a multinational cohort study

Max Peters, Utrecht, Netherlands, David Eldred-Evans, London, United Kingdom, Piet Kurver, Utrecht, Netherlands, Ugo Giovanni Falagario, Foggia, Italy, Martin J. Connor, London, United Kingdom, Joost J.C. Verhoeff, Utrecht, Netherlands, Giuseppe Carrieri, Luigi Cormio, Foggia, Italy, Pekka Taimen, Hannu J Aronen, Juha Knaapila, Ileana Montoya Perez, Otto Ettala, Turku, Finland, Armando Stabile, Giorgio Gandaglia, Nicola Fossati, Alberto Martini, Vito Cucchiara, Alberto Briganti, Milan, Italy, Anna Lantz, Solna, Sweden, Wolfgang Picker, Oslo, Norway, Erik Haug, Tønsberg, Norway, Tobias Nordström, Stockholm, Sweden, Mariana Bertoncelli Tanaka, Feargus Hosking-Jervis, Deepika Reddy*, Edward Bass, London, United Kingdom, Peter SN van Rossum, Utrecht, Netherlands, Suchita Joshi, Elizabeth Pegers, Kathie Wong, Henry Tam, David Hrouda, London, United Kingdom, Stuart McCraken, Sunderland, United Kingdom, Mathias Winkler, Stephen Gordon, Hasan Qazi, London, United Kingdom, Peter J. Boström, Ivan Jambor, Turku, Finland, Hashim U. Ahmed, London, United Kingdom

Introduction: Although multi-parametric MRI has high sensitivity for significant prostate cancer (sPCa), the lower specificity, particularly with equivocal (PIRADS 3) lesions, can result in numerous unnecessary biopsies. We aimed to develop and externally validate a simple scoring system for men with a visible MRI lesion to reduce the number of prostate biopsies.

Methods: 1,189 consecutive men with a visible MRI lesion were identified from a prospective prostate cancer diagnostic registry. A total of 14 clinical and radiological MRI variables known to be associated with risk of sPCa were evaluated. Using multivariable logistic regression, we derived a parsimonious risk score
for different definitions of sPCa.The performance of the risk score was internally validated and then externally validated across 6 international cohorts. For the final risk scores nomograms were created and analyses of clinical benefit were performed.

Results: For the primary endpoint (detection of =Gleason 3+4), the simplified RAPID risk score included age, PSA density (logged), prior negative biopsy, prostate volume and MRI Score (available at: https://rapidriskscore.shinyapps.io/RapidRiskScore1). The model had a discriminative ability (c-statistic or AUC) of 0.82 after internal validation which was similar in different years of data collection and in the external validation cohorts.This simplified model was compared to alternative models with additional clinical variables (including Afro-Caribbean ethnicity, DRE and a family history) and the clinical differences were negligible With thresholds for =Gleason 3+4 prostate cancer from 1-20% predicted by the model, the model was able to reduce the amount of biopsies up to 10.7%, while missing up to 1.9% of sPCa. The full models reduced biopsies up to 11.6%, albeit missing up to 2.4% sPCa.

Conclusions: The basic RAPID risk score is a simple 5-item score which provides a standardized tool for prediction of sPCa in men with a visible MRI lesion. It is available online as an app and its performance has been externally validated across multiple external, geographically distinct and independent datasets. In the
context of a risk-stratified MRI pathway, this tool can support patients and clinicians making decisions regarding the need for prostate biopsy.

Source of Funding: None