Northwestern University Feinberg School of Medicine
Introduction: Advanced biomarker tests and multiparametric prostate MRI (mpMRI) have improved risk stratification for detection of clinically significant prostate cancer (csPCa, ISUP Grade Group 2+). However, subsequent testing and detection of csPCa among men forgoing initial biopsy has not been well described. Here we characterize the subsequent detection of csPCa in patients who had an initial MRI without biopsy. Methods: We retrospectively identified biopsy-naïve men presenting with elevated PSA 2-20 ng/mL from March 2018 to June 2021 who received evaluation with mpMRI before biopsy consideration. Initial and follow-up clinicopathologic data including PSA, Prostate Health Index (PHI), mpMRI, and pathology reports were obtained. T-test, Chi-squared, Wilcoxon rank sum test, and multivariable logistic regression were performed. Results: 1494 men underwent mpMRI for initial evaluation, after which 463 (31%) did not pursue biopsy. On multivariable analysis, PSA density (PSAD) <0.1, PHI <55, and PIRADS 1-2 on mpMRI were significant predictors of omitting initial prostate biopsy. Of the men who did not initially receive biopsy, 353 men had minimum 6 months follow-up with median follow-up of 1.8 years. 15% (53/353) underwent repeat mpMRI. Overall, 2% of men (n=7) who originally omitted biopsy with follow-up were subsequently diagnosed with csPCa, six on subsequent prostate biopsy and one with incidental csPCa after holmium enucleation of the prostate (HoLEP). All patients diagnosed with csPCa had PIRADS 4 or 5 on repeat MRI. Conclusions: The subsequent detection rate of csPCa among patients not initially biopsied after mpMRI is low at 2%. Of the patients followed by serum biomarkers (i.e. PSA) with for cause MRIs, only the patients who developed PIRADS 4 or 5 lesions were found to have csPCa. Our institutional experience suggests that decisions to omit biopsy after MRI are often safe; additionally, if there is clinical suspicion leading to a repeat MRI, biopsy can again be omitted for mpMRIs scored as PIRADS 1-3. SOURCE OF Funding: None
