To evaluate the prevalence of clinically-significant prostate cancer (csPCa), defined as ISUP grade 2 or greater, in different PI-RADS score-PSA density cohorts at a specialist cancer centre.
Sequential biopsy-naïve patients with clinically-suspected PCa undergoing multiparametric MRI were enrolled in this retrospective cohort study. PSA density was calculated from MRI-derived gland volume and the most recent PSA value available prior to biopsy. PI-RADS scores were assigned prior to biopsy by one of five expert readers. As per standard of care, patients considered at low risk of csPCa were discharged, with others undergoing transperineal fusion biopsy with background sampling and additional cores taken from any target lesions.
Between July 2019 and April 2023, n=766 biopsy-naïve patients underwent multiparametric prostate MRI for suspected PCa. n=410 patients proceeded to biopsy (53.5%). Of those n=294 were diagnosed with PCa (71.7%), n=256 were ISUP grade 2 or greater (62.4%), and n=99 were ISUP grade 3 or greater (24.1%). We identified high rates of prostate cancer in those with low PSAD but MRI scored PI-RADS 4 or 5 (45.7% and 57.1%, respectively), and in patients with PSAD 0.10 or greater, a PI-RADS score of 5 was >90% likely to predict csPCa. n=145 patients (18.9%) were scored PI-RADS 3 with n=96 (66.2%) undergoing biopsy. We identified higher rates of csPCa in PI-RADS 3 patients than many previously reported studies, but this could be contributed to by the relative percentage of scans scored 3 versus 2. In addition, our rates of csPCa may be over-stated in those with lower PI-RADS scores as the decision to biopsy could have been influenced by clinical factors, not just PI-RADS score and PSA density (e.g. PSA kinetics, digital rectal examination and family history).
Confusion matrix indicating likelihood of clinically-significant prostate cancer (ISUP grade 2 or greater) by PSA density and PI-RADS score
Biopsy findings PSA density
Biopsy findings by PI-RADS score
PI-RADS score and PSA density provide complementary information which in combination can be helpful in deciding whether biopsy is required in patients with clinically-suspected PCa.
