Top Line: How effective is MRI-targeted focused ultrasound in controlling intermediate risk prostate cancer?
This Study: In this single arm, phase 2 study, 101 men with unilateral, MRI-visible, intermediate risk prostate cancer were treated with MRI-targeted focused ultrasound. Of note, 48% of clinically eligible patients were ultimately ineligible mostly (29%) due to ineligible target lesions. Most men had grade group 2 disease (78%). The ultrasound procedure was performed under general anesthesia with real-time MRI and ultrasound guidance with a median duration of 110 minutes. The target was the MRI-visible lesion and a 5 mm margin, which underwent thermal ablation to 60-70 degrees Celsius. MRI-targeted biopsy was performed 6 months and 24 months after treatment to determine if grade group ≥2 cancer was present after treatment. At 6 months, 95% had no evidence of grade group ≥2 disease, and at 24 months, 88% had no evidence of grade group ≥2 disease–at the site of the primary lesion. There’s more to the story, though. Whole prostate biopsies were also performed at 6 and 24 months where 76% and 60%, respectively, had no grade group ≥2 disease. When grade group 1 disease was included, only 40% had no cancer at 24 months. How does this compare to radiation? It’s not exactly an apples to apples comparison, but in a phase 1 prostate SBRT dose escalation study, the positive biopsy rate at 2 years was 19.2% at 35 Gy in 5 fractions and 7.7% at 40 Gy in 5 fractions. With respect to toxicity, 24% experienced hematuria and 15% experienced urinary retention.
TBL: MRI-targeted focused ultrasound appears effective at short-term control of solitary grade group 2-3 prostate cancer lesions in carefully selected men. However, in-prostate progression is common, and it is unclear if this approach provides effective long-term disease control.
- Ehdaie, Lancet Oncol 2022