Transurethral Water Vapor Ablation: Potential for a Novel Prostate Cancer Management Strategy

Purpose: Targeted and precise application of thermal energy stored in sterile water vapor is a novel approach to treat cancerous prostate tissue. We report safety and oncological results of transurethral hemigland vapor ablation in a prospective, single-arm study in men with unilateral, intermediate-risk localized prostate cancer. Patients and Methods: Men with biopsy confirmed Gleason Grade Group 2 (GG2) adenocarcinoma of the prostate, mean age 64.6 years, PSA 5.2 ng/mL, and prostate volume 46.8 cc on TRUS were enrolled. Using cystoscopy and transrectal ultrasound (TRUS) guidance, water vapor (~103°C) was delivered to prostate zones for hemigland ablation inclusive of cancers identified by multi-paramertric MRI (mpMRI) and biopsy. At 6-months, combined 12-core systematic and mpMRI fusion biopsy was performed. Subjects with no remaining GG2 disease were followed for 12 months. Those with residual or newly identified GG2 disease were eligible for a second vapor ablation and subsequent 6-month mpMRI fusion biopsy and were followed for at least 18 months after index treatment. Results: Fifteen subjects were successfully treated. At 6 months 4/15 subjects were identified for further management, two with residual GG2 cancer on the treated side, and two with newly identified GG2 cancer on the untreated contralateral side; one of two subjects with residual GG2 was ineligible for retreatment (unrelated myocardial infarction). Follow up at 12 to 18 months after initial or retreatment provided a final ≥GG2 negative biopsy in 14/15 (93.3%) subjects. Device or procedure-related adverse events (AEs) were mild/moderate and transient; none were serious AEs. Conclusion: Water vapor ablation has low morbidity. It is possible to successfully retreat residual disease or new lesions identified on surveillance with only transient mild to moderate adverse events and acceptable oncologic outcomes offering a new management strategy for localized prostate cancer.