Cancer Control Outcomes Following Focal Therapy Using High-intensity Focused Ultrasound in 1379 Men with Nonmetastatic Prostate Cancer: A Multi-institute 15-year Experience

Background: Focal therapy aims to treat areas of cancer to confer oncological control whilst reducing treatment-related functional detriment.

Objective: To report oncological outcomes and adverse events following focal high-intensity focused ultrasound (HIFU) for treating nonmetastatic prostate cancer.

Design, Setting, And Participants: An analysis of 1379 patients with ≥6 mo of follow-up prospectively recorded in the HIFU Evaluation and Assessment of Treatment (HEAT) registry from 13 UK centres (2005-2020) was conducted. Five or more years of follow-up was available for 325 (24%) patients. Focal HIFU therapy used a transrectal ultrasound-guided device (Sonablate; Sonacare Inc., Charlotte, NC, USA).

Outcome Measurements And Statistical Analysis: Failure-free survival (FFS) was primarily defined as avoidance of no evidence of disease to require salvage whole-gland or systemic treatment, or metastases or prostate cancer-specific mortality. Differences in FFS between D'Amico risk groups were determined using a log-rank analysis. Adverse events were reported using Clavien-Dindo classification.

Results And Limitations: The median (interquartile range) age was 66 (60-71) yr and prostate-specific antigen was 6.9 (4.9-9.4) ng/ml with D'Amico intermediate risk in 65% (896/1379) and high risk in 28% (386/1379). The overall median follow-up was 32 (17-58) mo; for those with ≥5 yr of follow-up, it was 82 (72-94). A total of 252 patients had repeat focal treatment due to residual or recurrent cancer; overall 92 patients required salvage whole-gland treatment. Kaplan-Meier 7-yr FFS was 69% (64-74%). Seven-year FFS in intermediate- and high-risk cancers was 68% (95% confidence interval [CI] 62-75%) and 65% (95% CI 56-74%; p = 0.3). Clavien-Dindo >2 adverse events occurred in 0.5% (7/1379). The median 10-yr follow-up is lacking.

Conclusions: Focal HIFU in carefully selected patients with clinically significant prostate cancer, with six and three of ten patients having, respectively, intermediate- and high-risk cancer, has good cancer control in the medium term.

Patient Summary: Focal high-intensity focused ultrasound treatment to areas of prostate with cancer can provide an alternative to treating the whole prostate. This treatment modality has good medium-term cancer control over 7 yr, although 10-yr data are not yet available.