REPEATED MRI SCANS DURING ACTIVE SURVEILLANCE FOR PROSTATE CANCER: NATURAL HISTORY OF PROSTATIC LESIONS AND UPGRADING RATES OVER TIME

Objectives To test upgrading rates in patients on Active Surveillance (AS) for prostate cancer (PCa) after serial multiparametric magnetic resonance imaging (mpMRI) scans. Materials and methods Retrospective analysis of 558 patients. Five different criteria of mpMRI progression were used: 1) PI-RADS score increase; 2) lesion size increase; 3) EPE score increase; 4) overall mpMRI progression; 5) number of criteria for mpMRI progression (0 vs. 1 vs. 2-3). Moreover, two definitions of PCa upgrading were evaluated:1) ISUP GG≥2 with >10% of pattern 4; 2) ISUP GG≥3. The estimated annual percent changes (EAPC) methodology depicted temporal trends of mpMRI progression criteria. Sensitivity, specificity, positive predictive (PPV) and negative predictive value (NPV) of mpMRI progression criteria were analysed. Multivariable logistic regression models tested PCa upgrading rates. Results Lower rates over time of all mpMRI progression criteria were observed. The NPV of serial mpMRIs spans from 90.5 to 93.5% (ISUP GG≥2 with >10% of pattern 4 PCa upgrading) and from 98 to 99% (ISUP GG≥3 PCa upgrading), according to the different mpMRI progression criteria. A PSA-D cut-off of 0.15 ng/ml/ml sub stratified those patients who could skip a prostate biopsy. In multivariable logistic regression models testing PCa upgrading rates, all five mentioned mpMRI progression criteria achieved independent predictor status. Conclusions: During AS, approximately 27% of patients experience mpMRI progression at first repeated scan. However, the rates of mpMRI progression decrease over time at subsequent mpMRIs. Patients with stable mpMRI findings and with PSA-D<0.15 ng/ml/ml could safely skip surveillance biopsies. Conversely, patients who experience mpMRI progression should undergo a prostate biopsy.