Introduction:

As patients with PI-RADS 5 lesions on prostate MRI are likely to have clinically significant prostate cancer on mpMRI/ultrasound fusion biopsy, there is a debate over the need for performing systematic biopsy (SB). In addition, it is unknown if any subset of men in this MRI risk assessment category could potentially avoid SB without missing clinically significant cancer while undergoing only targeted biopsy (TB). We, therefore, sought to assess the utility of TB in comparison with SB in detecting clinically significant prostate cancer in men with single versus multiple PI-RADS 5 lesions.

Methods:

We performed a retrospective study of patients who received MRI-ultrasound fusion prostate biopsy at a single institution from September 2015 to June 2021. We selected patients with at least one PI-RADS 5 lesion on mpMRI who underwent targeted biopsy of those lesions. Each patient meeting the above criteria was grouped into single PI-RADS 5 or multiple PI-RADS 5 (i.e., >1 PI-RADS 5 lesion) categories. The rates of cancer detection (any cancer and grade group (GG) ≥2) or missed cancer by either SB or TB were compared between the MRI classification groups.

Results:

The study cohort included 522 patients, including 473 (90.6%) with single PI-RADS 5 lesion and 49 (9.4%) with ≥2 PI-RADS 5 lesions (Figure 1). Detection rates of any cancer and GG ≥2 using TB were significantly higher in multiple PI-RADS 5 lesions compared with single lesion (any cancer: 91.8% vs 77.5%, P=0.01; GG ≥2: 81.6% vs 62.5%, P=0.008, Table 1). However, detection rates of any cancer and GG ≥2 using SB were similar between the two study groups. Moreover, SB missed GG ≥2 in 26.8% and 40.8% of single and multiple lesion groups, respectively (P=0.03). In both single and multiple PI-RADS 5 groups, the rate in which TB detected higher GG than SB, yet GG ≥2, was similar (12.6% vs 20.4%, P=0.12).

Conclusion:

Among patients with multiple PI-RADS 5 lesions, TB detected a greater proportion of prostate cancer when compared with those with a single PI-RADS 5 lesion. Given the higher rate of missed cancer by SB in this patient population, TB alone might be adequate to detect clinically significant prostate cancer in men with multiple PI-RADS 5 lesions.

Funding: N/A