Focal Therapy with High-Intensity Focused Ultrasound for Prostate Cancer: Three Year Outcomes from a Prospective Trial

Abstract

OBJECTIVE: To assess the oncological and functional outcomes of focal high-intensity focused ultrasound (HIFU) in treating localized prostate cancer (PCa), a 3-year prospective study was undertaken using periodic post-ablation saturation biopsies.

PATIENTS AND METHODS: Men with ≤ 2 lesions of grade group (GG) ≤ 3 PCa were eligible for participation. Additional criteria included a PSA ≤15 ng/mL, cT1c-T2, and a life expectancy of ≥10 years. The primary endpoint was failure-free survival (FFS), defined as absence of clinically significant PCa in-field or out-of-field on protocol-mandated saturation biopsy, no whole-gland or systemic salvage treatment, PCa metastasis, or PCa related death. Results are reported using two distinct definitions of csPCa: (1) the presence of any GG≥2 and (2) any GG≥3 or core involvement of ≥6 mm. Secondary endpoints were functional patient-reported outcome measurements addressing urinary, sexual, and bowel function.

RESULTS: 91 patients were included; 6 (7%) with GG1 and 85 (93%) with GG≥2. 83 (91%) underwent at least 1 follow-up biopsy. Biopsy attendance at 6, 12, and 36 months was 84%, 67%, and 51%, respectively. FFS at these timepoints for any GG≥2 PCa was 79% (95% CI 80-88%), 57% (95%CI 48-69%) and 44% (95%CI 34-56%), respectively. Using the second definition, FFS were 88% (95%CI 81-95%), 70% (95%CI 61-81%) and 65% (95%CI 55-77%), respectively. The 3-year cancer-specific survival was 100%, and freedom from metastasis was 99%. MRI (NPV of up to 89%, 95%CI 84-93%) and relative decrease of PSA values (p=0.4) performed poorly in detecting residual disease. Urinary and bowel assessment returned to baseline questionnaire scores within 3 months. 17 (21%) patients experienced meaningful worsening in erectile function. A significant decrease of PCa related anxiety was observed.

CONCLUSIONS: Focal HIFU treatment for localized PCa shows excellent functional outcomes with half of the patients remaining cancer-free after 3 years. Whole-gland treatment was avoided in 81%. Early follow-up biopsies are crucial to change or continue the treatment modality at the right time, while the use of MRI and PSA in detecting PCa recurrence is uncertain.