Background and objective: Magnetic resonance imaging(MRI) and targeted biopsies reduce overdiagnosis of prostate cancer(PC). It is uncertain how this strategy performs for low PSA levels. The objective was to investigate the PI-RADS distribution, frequency and characteristics of screen-detected PC with PSA of 1.8-<3ng/ml and 3-<10ng/ml.

Methods: In the population-based Göteborg-2 screening study, 17 974 men choose to participate by having a PSA(2015-2020). One-third of the participants(n=6006) were randomized to Arm 3, men with a PSA ≥1.8ng/ml were recommended MRI. Men with positive MRI(PI-RADS3-5) had four targeted biopsies from each MRI-visible lesion. Clinically significant PC was defined as Gleason score ≥3+4.

Key findings and limitations: 6006 men were included. Median age was 55.9 years. 670(11%) had PSA of 1.8-<3ng/ml(low-PSA group), median PSA 2.1ng/ml, and 377(6.3%) had PSA of 3-<10ng/ml(high-PSA group), median PSA 3.9ng/ml. PI-RADS scores of 3, 4, and 5 were observed in 7.8%, 15%, and 1.0% in the low-PSA group, and in 6.9%, 17%, and 5.3% in the high-PSA group, respectively. PC was found in 64 men (41%, 95%CI 0.33-0.49) with positive MRI findings in the low-PSA group, 33(21%) had Gleason 6 and 31(20%) had Gleason ≥7. In the high-PSA group, PC was detected in 61men (56%, 95%CI 0.46-0.66), 26(24%) had Gleason 6 and 35(32%) had Gleason ≥7. Limitations include results from only a single screening round.

Conclusions and clinical implications: A non-negligible number of men with PSA 1.8-3ng/ml have clinically significant PC. Whether a delay in the diagnosis of these tumors until they reached PSA ≥3ng/ml would impair their chance of cure remains to be evaluated.