Diagnostic Yield of Incremental Biopsy Cores and Second Lesion Sampling for In-Gantry MRI-Guided Prostate Biopsy.

Abstract

<b>BACKGROUND.</b> In-gantry MRI-guided biopsy (MRGB) of the prostate has been shown to be more accurate than other targeted prostate biopsy methods. However, the optimal number of cores to obtain during in-gantry MRGB remains undetermined. <b>OBJECTIVE.</b> The purpose of this study was to assess the diagnostic yield of obtaining an incremental number of cores from the primary lesion and of second lesion sampling during in-gantry MRGB of the prostate. <b>METHODS.</b> This retrospective study included 128 men with 163 prostate lesions who underwent in-gantry MRGB between 2016 and 2019. The men had a total of 163 lesions sampled with two or more cores, 121 lesions sampled with three or more cores, and 52 lesions sampled with four or more cores. A total of 40 men underwent sampling of a second lesion. Upgrade on a given core was defined as a greater International Society of Urological Pathology (ISUP) grade group (GG) relative to the previously obtained cores. Clinically significant prostate cancer (csPCa) was defined as ISUP GG 2 or greater. <b>RESULTS.</b> The frequency of any upgrade was 12.9% (21/163) on core 2 versus 10.7% (13/121) on core 3 (<i>p</i> = .29 relative to core 2) and 1.9% (1/52) on core 4 (<i>p</i> = .03 relative to core 3). The frequency of upgrade to csPCa was 7.4% (12/163) on core 2 versus 4.1% (5/121) on core 3 (<i>p</i> = .13 relative to core 2) and 0% (0/52) on core 4 (<i>p</i> = .07 relative to core 3). The frequency of upgrade on core 2 was higher for anterior lesions (<i>p</i> < .001) and lesions with a higher PI-RADS score (<i>p</i> = .007); the frequency of upgrade on core 3 was higher for apical lesions (<i>p</i> = .01) and lesions with a higher PI-RADS score (<i>p</i> = .01). Sampling of a second lesion resulted in an upgrade in a single patient (2.5%; 1/40); both lesions were PI-RADS category 4 and showed csPCa. <b>CONCLUSION.</b> When performing in-gantry MRGB of the prostate, obtaining three cores from the primary lesion is warranted to optimize csPCa diagnosis. Obtaining a fourth core from the primary lesion or sampling a second lesion has very low yield in upgrading cancer diagnoses. <b>CLINICAL IMPACT.</b> To reduce patient discomfort and procedure times, operators may refrain from obtaining more than three cores or second lesion sampling.