High-Intensity Focused Ultrasound (HIFU) Ablation of the Prostate

Educational Objectives

The goal of this program is to improve the management of prostate cancer using high-intensity focused ultrasound (HIFU). After hearing and assimilating this program, the clinician will be better able to:

1. Identify the indications, contraindications, and common complications for HIFU in prostate cancer.
2. Evaluate the efficacy and oncologic outcomes of HIFU.
3. Analyze the infield failure rate after HIFU.

Summary

Indications for high-intensity focused ultrasound (HIFU): predominantly in postradiation failures; concern for microscopic untreated disease outside the ablation zone is minimized; in patients with biochemical recurrence and locally recurrent prostate cancer, areas with unidentified disease have already been treated; novel imaging tools have high degree of sensitivity and can identify distant disease

Guidelines: recommend HIFU within a clinical trial (evidence supports its safety profile and oncologic control); National Comprehensive Cancer Network guidelines do not recommend HIFU in the primary setting owing to lack of long-term comparative data

Reimbursement: recently, a Category I Current Procedural Terminology code has been approved for HIFU and, reimbursements have increased; Advance Beneficiary Notice (waiver of liability) is no longer required

Patient selection: an ideal patient has unifocal, clinically significant disease (by volume or Gleason score [intermediate-risk disease]); the disease should be isolated from vital structures and visible with magnetic resonance imaging (MRI); absence of high-risk features (eg, gross extracapsular extension on MRI, T3 disease, vascular invasion) is desirable, but if features are present, radical primary therapy may be appropriate

Contraindications: gland size — relative; depends on the HIFU device (eg, Focal One [40-45 cm³], Sonablate [≈35 g]); limitations on gland size depend on the ability of the HIFU beam to reach the treated area (eg, in a 100-g prostate gland, HIFU beam is unlikely to reach an anterior tumor, however, it can reach a posterior tumor with visible margins within the field of view); the surgeon may wish to gain more experience before taking on more complex cases, eg, larger glands; large calcifications — typically present between the peripheral and transition zones; the HIFU beam cannot penetrate the calcification; energy deposition is inconsistent due to dispersion or reflection of the beam; transurethral resection of the prostate can remove the calcification and reduce the gland size; inflammatory bowel disease — HIFU is a transrectal procedure; other options include transurethral ultrasound ablation devices (eg, TULSA-PRO) and transrectal MRI-guided HIFU (eg, Insightec); prior radiation — in patients who received multiple prior doses of radiation, transrectal HIFU is not appropriate; brachytherapy seeds are a relative contraindication

Field of view: in the treatment arc, the red dots indicate individual focal ablation volumes; small ablation zones can be stacked to achieve a confluent ablation volume, and ensure precision; the energy mostly remains within the gland, and patients generally do not experience any secondary side effects from nontarget exposure

Common complications: urinary retention is typically seen in large volume and periurethral ablations and other focal modalities (eg, cryotherapy, irreversible electroporation) but not with HIFU; hematoma is rare; incidence of urethral sloughing has decreased with modern techniques; currently, circumferential ablation of urethra is not performed, and the urethral wall is preserved; unilateral ablation of the urethra is safe; no bladder neck contractures or strictures have been observed; indwelling catheters predispose to urinary tract infections; epididymo-orchitis is not uncommon; antibiotics reduce the rate of colonization; rectal complications — risk for rectourethral fistula (RUF) has been eliminated with safety techniques (eg, using cooling balloon, safe margin of treatment away from the rectum, allowing time for cooling); the rate of RUF is ≈0.4% (similar to the rate of rectal injury with radical prostatectomy [RP])

Avoiding rectal complications: avoid retreating the posterior zone (with experience, overlap between the zones can be increased to deliver a higher dose of energy); planning ≈1 mm within the capsule can deliver full energy and ablation up to the capsule; avoid near-field heating (accumulation of heat proximal to the target area); monitor carefully and ensure that fat does not become more hyperechoic; pause for cooling

Focal therapy (FT) vs RP: Shah et al (2021) performed a propensity score-matched trial using RP and FT databases; matched variables included use of neoadjuvant hormone treatment, age, prostate-specific antigen, tumor volume, Gleason score, laterality, and year of treatment; the primary endpoint was failure-free survival (FFS); failure was defined as requiring local salvage therapy (>2 focal ablative treatments) or systemic therapy, and development of metastasis; >66% of patients had Grade Group (GG) ≥2; in the FT group, most patients received HIFU and some received cryotherapy; FFS with RP was similar to FT over 8 yr; with a stricter definition of FFS (only one initial ablative event allowed), FFP with PR vs FT was similar (3 yr, 76% vs 82%; 5 yr, 73% vs 71%; 8 yr, 70% vs 63%)

Oncologic outcomes after HIFU: Stabile et al (2019) — analyzed patients who were treated with HIFU (median follow-up, 36 mo; >80% had GG ≥2); biopsy FFS was 86% at 24 mo, 64% at 60 mo, and 54% at 96 mo; radical treatment-free survival was 81% at 96 mo; Reddy et al (2022) — reported oncologic outcomes after FT with HIFU (median follow-up, 32 mo; 65% of patients had intermediate-risk disease; 28% had high-risk disease); at 5 yr, FFS in the intermediate-risk group (IRG) was 83% vs 79% in the high-risk group (HRG; 68% vs 65% at 7 yr); for both groups, whole gland or systemic treatment-free survival was 84% at 5 yr and 73% at 7 yr

HIFU in the context of RP: after RP, the prostate cancer-specific survival for a patient on the lower end of the high-risk spectrum is 80% at 15 yr, and progression-free survival is 38% at 5 yr and 25% at 10 yr; HIFU provides an option with reasonable cancer control and cure

Functional outcomes: incontinence rate is low (pad-free continence); patients with borderline baseline sexual function may experience erectile dysfunction; risk for bowel dysfunction or urinary stricture is low; ejaculatory function is preserved in some men after HIFU

Readings

Bakavicius A, Marra G, Macek P, et al. Available evidence on HIFU for focal treatment of prostate cancer: a systematic review. Int Braz J Urol. 2022;48(2):263-274. doi:10.1590/S1677-5538.IBJU.2021.0091; Crouzet S, Murat FJ, Pommier P, et al. Locally recurrent prostate cancer after initial radiation therapy: early salvage high-intensity focused ultrasound improves oncologic outcomes. Radiother Oncol. 2012;105(2):198-202. doi:10.1016/j.radonc.2012.09.014; Napoli A, Alfieri G, Scipione R, et al. High-intensity focused ultrasound for prostate cancer. Expert Rev Med Devices. 2020;17(5):427-433. doi:10.1080/17434440.2020.1755258; Reddy D, Peters M, Shah TT, et al. Cancer control outcomes following focal therapy using high-intensity focused ultrasound in 1379 men with nonmetastatic prostate cancer: a multi-institute 15-year experience. Eur Urol. 2022;81(4):407-413. doi:10.1016/j.eururo.2022.01.005; Shah TT, Reddy D, Peters M, et al. Focal therapy compared to radical prostatectomy for non-metastatic prostate cancer: a propensity score-matched study. Prostate Cancer Prostatic Dis. 2021;24(2):567-574. doi:10.1038/s41391-020-00315-y; Stabile A, Orczyk C, Hosking-Jervis F, et al. Medium-term oncological outcomes in a large cohort of men treated with either focal or hemi-ablation using high-intensity focused ultrasonography for primary localized prostate cancer. BJU Int. 2019;124(3):431-440. doi:10.1111/bju.14710.

Disclosures

For this program, the following relevant financial relationships were disclosed and mitigated to ensure that no commercial bias has been inserted into this content: Dr. George is a consultant for Sonablate. Members of the planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. George was recorded at Southwest Prostate Cancer Symposium, held April 13-15, 2023, in Scottsdale, AZ, and presented by Grand Rounds in Urology. For more information about upcoming CME activities from this presenter, please visit Grandroundsinurology.com. Audio Digest thanks the speakers and Grand Rounds in Urology for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.75 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.75 CE contact hours.

Lecture ID:

UR470601

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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