Diagnosing Prostate Cancer: The Role of Intravesical Prostatic Gland Protrusion on Accuracy of Prostate Biopsies

Purpose: We evaluated the association between intravesical prostate protrusion (IPP) and the detection rate of clinically significant prostate cancer (csPCa) on magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion targeted biopsy (TB). Materials and Methods: A total of 538 consecutive men who underwent MRITRUS fusion TB and concomitant systematic biopsy were evaluated. IPP on MRI was independently measured by 4 blinded reviewers. The primary outcome was per-lesion detection of csPCa on TB. We assessed the association between IPP and csPCa detection on TB, controlling for age, prostate specific antigen, Prostate Imaging Reporting and Data System(R) (PI-RADS(R)) score, prostate volume, targeted cores sampled and previous biopsy experience. Results: A total of 847 PI-RADS 3 or greater lesions were targeted across 570 biopsies. Intra- and interrater reliability for measuring IPP was strong. A total of 81 (14.2%), 127 (22.3%), 237 (41.6%) and 125 (21.9%) men had 0, small, medium and large IPP, respectively. A total of 230, 392 and 196 lesions were PI-RADS 3, 4 and 5, respectively. Of the lesions 198 (34.7%) had csPCa on TB. The overall relationship between IPP size and csPCa found on TB was not significant; however, large IPP is associated with a significantly lower rate of csPCa detection than 0 IPP (p=0.007). Every mm increase in IPP is associated with a 5.6% decrease in the odds of csPCa detection on TB (p=0.004) and a 66.5% decrease in odds of detection in large IPP compared to 0 IPP (p=0.003). Conclusions: As the size of the IPP and volume increase, there is a decrease in the detection rate of csPCa on MRI-guided TB. These findings may be driven by poor MRI-TRUS co-registration and prostate asymmetry.