780 Minimizing the Gleason score upgrade from biopsy to prostatectomy specimen through mpMRI and template mapping fusion biopsy

Abstract

INTRODUCTION AND OBJECTIVES: Precise risk stratification is essential in times where alternative treatment options to radical prostatectomy (RP) such as active surveillance, brachytherapy, radiotherapy and focal treatment of prostate cancer (PC) are available. However, the current concordance of conventional transrectal prostate biopsy (PB) regarding Gleason score (GS) is low 53-69%, when compared to RP specimens. Multiparametric MRI (mpMRI) of the prostate and fusion transperineal prostate mapping (TPM) biopsy might allow increasing the concordance facilitate the decision making. METHODS: A total of 348 patients were included in this retrospective analysis. Pathological reports were analyzed from patients who underwent radical prostatectomy (RP) and compared to GS acquired by PB or TPM after mpMRI. MpMRI fusion TPM was performed by taking biopsy cores from 20 predefined regions of the prostate and from MRI suspicious lesions after fusion. RESULTS: Patients with PB before RP demonstrated an overall increase in GS of 30% and a significant increase of 2 GS steps was detectable in 15%. Patients with a mpMRI and TPM demonstrated an increase in GS only 16.6% with maximally one GS step. This difference is even more pronounced if GS 3+4 and 4+3 are not differentiated and summarized to GS 7 only. In this case the GS upgrade is 6.3% for TPM compared to 22.8% for PB. However, the amount of downgraded GS after RP is higher for TPM (TPM 31.2% vs. PB 14.0%). The detailed analysis of the TPM group showed that GS upgrades were limited to GS 6 and 7a. None of the >7b GS demonstrated a GS upgrade indicating the superior precision of the extended TPM. CONCLUSIONS: MpMRI with TPM allows for a more precise risk stratification by displaying the true GS more often. Optimal diagnosis with minimal risk of underestimating the disease burden is crucial to select patients for focal treatment and to prevent over-treatment by radical therapy options. This novel diagnostic strategy will help counselling patients before any treatment strategy.