Oncology - Prostate
Introduction & Objective :
To determine if spatial distribution of multiparametric MRI- Transrectal Ultrasound (mpMRI-TRUS) fusion biopsy cores to the index lesion reveals trends in the detection of intra-lesion Gleason heterogeneity and a more optimal biopsy strategy to sample the prostate.
A prospectively maintained single-institution database was analyzed for patients who underwent mpMRI fusion with targeted and systematic 12-core biopsy in 2017. Index lesion was defined as the lesion with longest diameter on T2W-MRI. In order to improve diagnostic accuracy of fusion biopsies, we changed our template for biopsy in July 2017. In cohort 1 (starting July 2017), fusion biopsy cores biopsies were taken in areas in the center of the target as well as 1cm laterally on each side. For cohort 2 (prior to July 2017), targeted biopsies were taken from the center of the lesion only. Gleason heterogeneity was defined as a difference in the maximum Gleason score obtained from fusion cores in the center of the index lesion vs cores obtained from the periphery (cohort 1), or any difference in maximum Gleason score obtained from fusion cores targeted to the index lesion (cohort 2) compared with systematic 12 cores TRUS biopsy. Chi square test was used to compare Gleason heterogeneity between cohorts.
99 consecutive patients (35 and 64 in cohorts 1 and 2, respectively) with median age (SD) and PSA of 66.9 (±5.9) and 9.7 (±8.2) respectively, were included. Mean index tumor diameter was 16.4(±4.9) and 15.8 (±6.1), respectively (p=0.047). Age, PSA, PI-RADS score, pre-operative MRI lesion size and Gleason score from 12-core biopsy were not significantly different between cohorts. Median number of biopsy cores taken from cohort 1 was 4 (2 center, 2 periphery) and 2 in cohort 2. Gleason heterogeneity was observed at a significantly higher rate in cohort 1 vs cohort 2 (58% vs 24%; p=0.041). In cohort 1, Gleason score from cores obtained from the center of the lesion were higher than Gleason scores obtained from the periphery of the targeted lesion in 57% of cases.
Conclusions : Presently, there is no consensus on the spatial placement or number of biopsy cores within lesions during mpMRI-TRUS fusion biopsy. Since changing our fusion biopsy strategy, we demonstrate that there is tumor heterogeneity in biopsy specimens, and that increased number of cores, as well as cores focused to the center of the largest lesion in the prostate, yield higher Gleason scores than cores focused to the periphery of the lesion. These results may contribute to the spatial recommendations for biopsy cores in the future.