Oncology - Prostate
Introduction & Objective :
The Prostate Imaging Reporting and Data System (PI-RADS) v 2.0 instructs the radiologist to take into account tumor location; however, the final PI-RADS score is agnostic to whether the tumor is in the peripheral (PZ) or the transitional zone (TZ) of the prostate . As such, we sought to assess whether a given final PI-RADS score communicates the same level of risk for patients with tumors in the PZ vs. TZ.
Methods : Using a prospectively maintained database, we identified men who underwent targeted fusion prostate biopsy using the UroNav System (Invivo) at our institution. Patients underwent mp-MRI at our institution or at a referring institution. Targetable lesions on multiparametric MRI performed at outside facilities were not formally re-interpreted by our own institution’s radiologists, but were traced for biopsy. PI-RADS score, tumor location, and pathologic findings were indexed.
Results : 457 biopsies (in 444 men) performed at our institution qualified for inclusion into our study (median age= 64, IQR 59-69 , median PSA= 6.28, IQR 4.5-9.2). 231 targeted biopsies were taken from the PZ, while 226 targets were from the TZ. Significant cancers were defined as Gleason Group ≥ 2. A two-sided Fisher’s exact test was used to determine the association between a given PI-RADS grade and biopsy pathology (Figure 1). Biopsies of lesions in the TZ with PIRADS score of 5 were more likely to be positive for cancer than similar PZ counterparts. Meanwhile, PIRADS score 3 and 4 lesions were more likely to be consistent with malignancy if they appeared in the PZ.
Conclusions : A given PI-RADS Score appears to have different test characteristics for detection of prostate cancer based on its location. Better understanding of this clinical nuance is needed.