High intensity focused ultrasound may be superior to radiation therapy for the treatment of early stage prostate cancer

Abstract

Arguing against the Proposition is Gert De Meerleer, M.D., Ph.D. Dr. Meerleer obtained his M.D. degree in 1994 and his Ph.D. in Radiation Oncology in 2000, both from Ghent University, Belgium. He currently practices as radiation oncologist and Professor at Ghent University Hospital where he is responsible for the treatment of urological and gynecological malignancies. He has published extensively in radiotherapy, especially the use of IMRT for the treatment of prostate cancer. He is an active participant in ESTRO and is currently Director of the ESTRO multidisciplinary teaching course on prostate cancer. There are many options for the treatment of localized prostate cancer, and each has its own unique risks and benefits. For early stage prostate cancer, HIFU may be superior to radiation therapy—either external beam radiation therapy (EBRT) or brachytherapy (LDR or HDR). HIFU is a minimally invasive treatment option for prostate cancer that uses either a transrectal or transurethral applicator coupled with image guidance to focus high intensity ultrasound energy in the prostate.1 At a very precise and targeted location identified using ultrasound or MRI guidance, the temperature is rapidly elevated to 55–70 °C; a lethal thermal dose which causes irreversible tissue destruction.2 MRI coupled with HIFU provides precise image guidance for these procedures as well as near real-time temperature feedback via MR-thermometry,3 making accurate destruction of prostate target tissue practical. Although HIFU remains investigational in the United States for prostate cancer, several thousand patients have been treated in trials outside of the United States.4–6 Clinical HIFU protocols typically involve ablation of the entire prostate gland and are indicated especially for nonsurgical candidates such as elderly men who are unwilling or unable to undergo radical prostatectomy or receive radiation therapy for locally advanced or recurrent disease.7 HIFU has several practical benefits as compared to RT. While both are minimally invasive procedures, HIFU can deliver a treatment in a single session. The effects of HIFU are immediate; the targeted tissue is ablated with this technique. HIFU uses nonionizing ultrasound energy, which does not suffer from the same risk of late radiation effects as with ionizing beams; thus HIFU can be repeated if needed and can be combined with EBRT.8 MR-guided HIFU provides the unique capability to perform temperature feedback and “dosimetry” in situ and imaging immediately postprocedure to verify treatment, thus providing confirmation of complete destruction of a defined target region. The superior benefits of HIFU are demonstrated by the very promising reported outcomes in the studies performed outside the United States. These report excellent biochemical control and, while side-effects (urinary stricture, retention, incontinence, impotence) are reported, they are at a rate lower than for RT.9–14 These early results, for mainly low- and intermediate-risk cancers (T1-T2 N0M0 disease, Gleason score of < 7, PSA level <15 ng/mL, and a prostate volume <40 mL),12 and for outcomes without the long, widespread clinical adoption as compared to radiation therapy, have been acceptable, but would benefit from further confirmation in prospective multicenter trials, several of which are now underway. HIFU also holds promise for focal ablation of defined regions of prostate cancer.15 Focal use of HIFU should reduce the adverse sexual, urinary, and bowel effects of whole gland ablation. New techniques under development for MRI-guided HIFU treatment enable the integration of diagnosis, planning, and treatment of localized prostate cancer using MRI and could transform the management of this disease into a minimally invasive outpatient procedure with high precision and a low-level of side effects. High-dose external beam radiotherapy has resulted in excellent biochemical control rates (BCRs) of >90% in low risk prostate cancer patient