Abstract No. 91 MRI-Guided Cryoablation of Oligo-Metastatic Prostate Cancer to the Pelvic Lymph Nodes

Abstract

To demonstrate feasibility and short-term follow-up of using MR-guided cryoablation for treatment of oligo-metastatic prostate cancer to pelvic lymph nodes. Retrospective review is conducted for patient’s treated with MR-guided cryoablation from September 2018 to December 2021 for solitary prostate cancer metastasis to the pelvic lymph node as identified by PET choline and/or PET PSMA imaging. Patients underwent MR-guided cryoablation using a transperineal needle placement under general anesthesia. Cryoablation was performed with continuous MR imaging monitoring so that the iceball was grown to encompass the lesion with margins as permitted based on adjacent structures (i.e., ureter, obturator nerve, sciatic nerve). Patients were discharged the same day. PET Imaging and PSA were performed every 3 months post-ablation with MRI of the pelvis as needed. Percent change in PSA for patients without new metastatic disease at 3-month PET/CT was assessed using a paired t-test. Review demonstrated 11 patients with 12 procedures during this time frame. Baseline PSA was 1.47 ± 2.79 ng/mL. All 12 procedures had negative 3-month post-ablation PET imaging based on local response to treatment. Post-ablation gadolinium contrast T1 weighted MRI showed lack of enhancement. Among the 7 patients with no new metastatic or prostatic bed disease, there was a significant percent decrease in PSA at 3 months post-ablation (-47.2% ± 29.5%; P = 0.003). MR-guided cryoablation can be utilized for the treatment of oligo-metastatic prostate cancer to the pelvic lymph nodes with good short-term results.