Mp46-02 detailed Analysis of Mri Concordance With Prostatectomy Histopathology Using Deep Learning-Based Digital Pathology

Abstract

INTRODUCTION AND OBJECTIVE: Focal therapy of prostate cancer (PCa) is of increasing interest, but a convenient metric to determine success is lacking. We evaluated the role of PSA and MRI in determining tissue resolution of PCa after partial gland ablation (PGA).METHODS: 138 men with unilateral, clinically significant PCa (csPCa) underwent a prospective PGA trial employing cryotherapy (CRYO, N[91) or high intensity focused ultrasound (HIFU, N[47) between 2/2016 and 8/2020. PSA determinations were performed prior to PGA and at 3, 6, 12 and 18 months after treatment. MRI and MRIguided biopsy (MRGB) were performed at baseline, 6 and 18 mos. The analysis was powered to test if !80% reduction in PSA from baseline predicts absence of ! GG2 in the ablation zone at 6 mos in 90% of men. This metric was chosen because it appears to predict long-term 'failure free survival' (Stabile, 2020). Primary outcomes were presence of ! GG2 on MRGB at 6 mo. and adverse event profile. Secondary outcomes were effects on MRI and absence of !GG2 at 18 months All biopsy sessions included systematic, targeted, and tracked biopsy. 6-mo biopsy was ipsilateral to treatment; 18-mo biopsy was bilateral (Fig. 1).RESULTS: All 138 men underwent PGA successfully, 131 completing 6-mo and 70 completing 18-mo MRGB (total 339 biopsy sessions). At 6-mo biopsy, 75% of patients (99/131) were free of csPCa. An 80% decline in PSA from baseline to nadir correctly ruled out csPCa in 85% of patients (NPV 85%). However PPV was only 29% and AUC only 0.58. PSA decline was similar among CRYO and HIFU cohorts and was independent of treatment outcome (Fig. 2). Disappearance of MRI lesions, seen in 72% (93/130), was also unrelated to outcome. PSA density was more predictive of outcomes than other permutations of PSA. At 18 months, using the biopsy criterion, 60% of patients (42/70) were free of csPCa. No serious adverse events were encountered.CONCLUSIONS: Following PGA, tissue resolution of csPCA (75% at 6 months, 60% at 18 months) was not completely ascertained by PSA or MRI. MR-guided biopsy should be used to determine success or failure of PGA during continued surveillance.