Targeted And Perilesional Or Systematic Biopsy In Prostate Cancer

In prostate cancer (PCa), the descriptor 'clinically significant' is widely used to differentiate PCa that may cause morbidity or death in a specific patient from types of PCa that rarely do. The definition of significant vs. insignificant is a balance between tumor and patient factors. In current guidelines and literature, it is widely accepted that insignificant PCa corresponds to almost all men with an International Society of Urological Pathology (ISUP) grade group 1, while clinically significant PCa is defined as any ISUP grade group ≥2.

This distinction is particularly important as insignificant PCa is more common than significant PCa. The detection of insignificant PCa has increased since the introduction of the prostate-specific antigen (PSA) test in the 1990s, and poses several problems of over-diagnosis and over-treatment, considered to be major drawbacks of population-wide screening and individual early detection. It is well known that insignificant PCa has very low risk of local and distant progression, and an active surveillance associated with a deferred curative treatment protocol based on clear indicators of disease progression, is now recommended for all insignificant PCa. However, higher detection of insignificant PCa can lead to patient anxiety about inclusion in an active surveillance protocol, potential further damage from repeated surveillance biopsies and higher healthcare costs. Therefore, our objective during PCa screening is to maintain the detection of clinically significant PCa while decreasing the diagnosis of insignificant PCa.

Magnetic Resonance Imaging (MRI) is currently indicated prior to prostate biopsy and is used to identify and locate suspicious lesions for clinically significant PCa. Indeed, correlation with radical prostatectomy specimens shows that MRI has good sensitivity for the detection and localization of ISUP grade group ≥ 2 PCa. Several recent large-scale randomized controlled trials have shown that pre-biopsy MRI and MRI-targeted biopsy are the best modality for increasing the detection of clinically significant PCa, while reducing the detection of clinically insignificant PCa, in comparison with a systematic biopsy scheme.

Radiologists use multi-level scoring systems according to the Likert scale principle; where the presence of clinically significant prostate cancer in a lesion can be subjectively categorized as highly unlikely to highly likely, with a varying number of subdivisions. The 1 to 5 scale according to the Prostate Imaging - Reporting and Data System (PI-RADS) version 2.1 provides guidance for radiologists with more objective criteria and is currently most often used.

The PI-RADS score is used in clinical practice as a triage test to indicate the need for prostate biopsy. Patients with a PI-RADS score of 1 or 2 have a very low risk of having clinically significant PCa (<5%), and prostate biopsy is generally not performed in these cases to avoid diagnosing insignificant PCa (20%). The same principle applies to patients with a PI-RADS 3 lesion. In a multicenter cohort of 1476 men with PI-RADS 3 lesions, the prevalence of ISUP grade group ≥ 2 was 18.5%. Applying a PSA density cut-off of 0.15 ng/mL/cc, 817 biopsy procedures (58.4%) would have been avoided at the cost of missing ISUP grade group ≥ 2 PCa in only 91 men (6.5%) and ISUP grade group 1 PCa would not have been detected in 115 men (8.2%). Consequently, current guidelines recommend avoiding biopsy in patients with a PI-RADS 3 lesion and low PSA density. In patients with a PI-RADS 4 or 5 lesion, prostate biopsy is strongly indicated, as the prevalence of clinically significant PCa ranges from 31% to 77%.