Diagnostic Effects of Omitting Systematic Biopsies in Prostate Cancer Screening.

Background and objective: The optimal biopsy strategy in prostate cancer screening is unknown. This study aims to assess the diagnostic effects of omitting systematic biopsies in a screening cohort.

Methods: We used data from the STHLM3-MRI trial. A total of 7609 men aged 50-74 yr were randomised to undergo magnetic resonance imaging (MRI) if having an elevated risk of prostate cancer (prostate-specific antigen [PSA] ≥3 ng/ml or Stockholm3 ≥11%). Participants with Prostate Imaging Reporting and Data System (PI-RADS) ≥3 underwent targeted and systematic biopsies. Cancer detection rates from combined and targeted-only biopsies were presented as a risk ratio (RR). Subgroup analyses were stratified by age, PSA density (PSAd), and PI-RADS. Differences in reclassification rates at radical prostatectomy were calculated.

Key findings and limitations: The median age of the participants was 66 yr (interquartile range: 61-71) and PSA 3.8 ng/ml (2.9-5.8). Out of 395 men undergoing combined biopsies, 52 (13.2%) had International Society of Urological Pathology (ISUP) grade group (GG) 1 and 230 (58%) had ISUP GG ≥2 prostate cancer. Omission of systematic biopsies reduced cancer detection rates (RR of ISUP GG 1: 0.83 [95% confidence interval 0.64-1.07]; ISUP GG ≥2: 0.85 [0.81-0.90]; and ISUP GG ≥3: 0.86 [0.79-0.95]). Each case of averted ISUP GG 1 cancer was associated with 3.8 cases of missed ISUP GG ≥2 and 1.1 case of ISUP GG ≥3 cancer. Detection of fewer ISUP GG ≥2 cases than the number of avoided ISUP 1 cancer cases was observed in all subgroups when systematic biopsies were omitted. Using PSAd ≥0.05 ng/ml² as a cut-off for a biopsy resulted in the same numbers of ISUP GG 1 tumours saved, with higher detection rates of ISUP GG ≥2 tumours. In 146 men undergoing radical prostatectomy, 46 (31.5%) versus 28 (19.2%) were upgraded following targeted biopsies versus a combined biopsy strategy (p < 0.05).

Conclusions and clinical implications: Complete omission of systematic biopsies in prostate cancer screening is associated with decreased detection of significant cancer, while reducing overdetection of insignificant cancer to a smaller extent. This strategy also increased the risk of histopathological misclassification.

Patient summary: In a prostate cancer screening setting, we examined the diagnostic effects of systematic biopsies in addition to targeted biopsies in men with suspicious magnetic resonance imaging lesions. We found that exclusion of systematic biopsies led to reduced detection of clinically significant prostate cancer. Our findings emphasise the importance of incorporating systematic biopsies alongside targeted biopsies for improved diagnostic outcomes.