TULSA-PRO: MRI-guided HIFU prostate cancer treatment shows promise
HIFU or high-intensity focused ultrasound was approved by the FDA in October 2016 for the treatment of localized prostate cancer. HIFU destroys prostate cancer through the delivery of precise and focused sound waves to a targeted spot of diseased prostate tissue. This technology uses ultrasound energy, not radiation, to destroy the targeted tissue.
With the current systems delivering HIFU, the ultrasound energy, or sound waves, is transmitted through the rectal wall and focused at desired locations within the prostate identified by MRI (magnetic resonance imaging) and confirmed by ultrasound. This targeted and minimally invasive approach to treating prostate cancer leaves the healthy tissue untouched and unharmed and minimizes the chance of side effects. I have referred several patients to this procedure with excellent results in terms of tumor control and minimal side effects.
At the RSNA 2019 in Chicago this year, promising findings were presented from a multi-center study using a new generation of HIFU with MRI guidance to treat prostate cancer and benign enlargement of the prostate gland.
The outpatient procedure is known as MRI-guided transurethral ultrasound ablation (TULSA) and is designed to deliver precise doses of sound waves to diseased prostate tissue and spare healthy nerve tissue surrounding the prostate. Results from this 12-month TULSA-PRO Ablation Clinical Trial showed minimal side effects for patients and exceptional success in reducing or eliminating the cancer.
Unlike with other ultrasound systems that deliver HIFU, with TULSA the ultrasound ablation process can be monitored in real-time with immediate MRI feedback of the thermal dose and efficacy.
The company that markets the TULSA-PRO system, Profound Medical, recently received U.S. Food and Drug Administration 510(k) clearance for prostate tissue ablation. The system also is approved for clinical use in Europe.
TULSA-PRO procedures begin with the insertion into the urethra of a rod-shaped device that includes 10 ultrasound-generating elements that can cover the entire prostate gland. One or more of the components then transmits sound waves to heat and destroy the targeted prostate tissue. Software automatically controls the components to adjust the shape, direction, and strength of the therapeutic ultrasound beam. The entire procedure takes place in an MRI scanner so that clinicians can closely monitor treatment and the degree and location of heating.
YouTube Animation of TULSA treatment
For the study being presented at RSNA 2019, researchers enrolled 115 men (median age, 65; range, 59 to 69) who had median prostate-specific antigen (PSA) levels of 6.3 ng/mL (range, 4.6 to 7.9 ng/mL). These patients all had localized low- or intermediate-risk prostate cancer, which was confined to the prostate gland. Clinicians delivered the TULSA treatment to the entire gland over an average time of 51 minutes.
Through TULSA, prostate volume among the subjects decreased on average from 39 cubic cm before the treatment to 3.8 cubic cm 12 months later. In addition, clinically significant cancer was eradicated in 80% of the patients, with 72 (65%) men showing no signs of any cancer in a biopsy after one year. Overall PSA levels also decreased by a median of 95% at one-year follow-up, and there were low rates of severe toxicity and no bowel complications.
TULSA provides the ability to control HIFU with much more precision which allows for preservation of continence and sexual function.
The study also supports the use of MRI for post-treatment monitoring of patients who undergo TULSA. MRI had a negative predictive value of 93% to 96% for detecting residual cancer at one year after treatment, which makes the modality very accurate for ruling out disease recurrence in patients.
TULSA is currently available in Europe and in a few locations in the U.S. While this is not yet covered by insurance, sites where this technology may be available is likely to expand quickly. At this time sites that may offer TULSA include UCLA, Johns Hopkins, Vanderbilt University, University of Chicago, Indiana University, William Beaumont Hospital and the University of Texas Southwestern and Vituro Health in Birmingham, AL.