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

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).

A total of 538 consecutive men who underwent MRI-TRUS 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® (PI-RADS®) score, prostate volume, targeted cores sampled and previous biopsy experience.

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).

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.