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CHICAGO -- A minimally invasive MRI-guided procedure that uses therapeutic ultrasound effectively treated prostate cancer with nominal side effects, a researcher said here.

In the TULSA-PRO ablation clinical trial (TACT), 115 men with localized low or intermediate risk, gland-confined prostate cancer underwent MRI-guided transurethral ultrasound ablation (TULSA). Prostate volume in the study group decreased on average from 39 cubic centimeters pre-treatment to 3.8 cubic centimeters a year after treatment, according to Steve Raman, MD, of the University of California Los Angeles.

Overall, clinically significant cancer was eliminated in 80% of the study participants, and 65% had no evidence of any cancer at biopsy after 1 year, Raman reported at the Radiological Society of North America annual meeting.

In addition, blood levels of prostate-specific antigen (PSA) fell by a median of 95%, and there were low rates of severe toxicity and no bowel complications.

"We saw very good results in the patients, with a dramatic reduction of over 90% in prostate volume and low rates of impotence with almost no incontinence," Raman said in a press statement.

Also, TULSA has the benefit of allowing further treatment if needed. If TULSA fails, then the procedure can be repeated, and more aggressive invasive approaches like surgery and radiation therapy can still be used, he told MedPage Today.

"This is exciting," Raman said. "I want a system that I would use to treat my own brother or father. I want to be sure that when I am treating someone, for whom I could just be watching their tumor, I am not doing any harm. We don't want to make their quality of life worse and miserable. This is the kind of device that offers that safety profile."

In August 2019, Profound Medical announced that the TULSA-PRO device received for the ablation of prostate tissue based on TACT results. The device was approved in in 2016.

TULSA-PRO uses a rod-shaped device that is inserted into the urethra, and has 10 ultrasound-generating elements that can cover the entire prostate gland. One or more of the elements are used to send out sound waves that heat and destroy the target prostate tissue. The elements are controlled automatically by a software algorithm that can 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 assess the degree and location of heating.

"Unlike with other ultrasound systems on the market, you can monitor the ultrasound ablation process in real time and get immediate MRI feedback of the thermal dose and efficacy," Raman explained. "It's an outpatient procedure with minimal recovery time."

"The procedure takes up to 90 minutes depending on the amount of treatment being performed," he told MedPage Today.

In the trial, 65% of the men (median age 65) were diagnosed with Gleason 4 prostate cancer (Gleason group 2 cancer), while 20% were high volume Gleason group 1 cancer. Patients with high grade cancer (above Gleason 4) were excluded from the trial, Raman noted.

Some of the trials patients are 2 to 2.5 years out from treatment, Raman said. While no metastatic disease has been reported to date, it is still too early to tell, he cautioned.

Raman reported that about 7% of the patients experienced grade 3 adverse events, mostly infection or urinary retention. "They were self-limiting and they all resolved," he stated.

Also, about 2.6% of patients treated with TULSA experienced moderate urinary incontinence, and the risk of incontinence and impotence with the device appeared to be less than with conventional treatment, he said. "Typically for any prostate treatment, patients have problems with incontinence and impotence ... Of the 115 patients, 92 had potency at baseline, and 75% of that group with potency, at 12 months. had 80% of sexual function retained," he said.

Raman's group noted that TULSA could also be used to treat benign enlargement of the prostate gland. "This treatment transcends traditional specialties so we need people to work together," he stressed. "We need interventional radiologists to work with urologists to make this happen, and they do not necessarily all play in the same sandbox."

Federico Bruno, MD, of the University of L'Aquila in Italy, told MedPage Today that "patients with prostate cancer who have a diagnosis of an intermediate grade -- a cancer that sometimes doctors will 'watch and wait' -- are the patients for which focused ultrasound is an option."

"In the past decade, use of focused ultrasound has exploded across multiple fields, including treatment for tremors, prostate cancer, and even in getting drugs to cross the blood-brain barrier for treatment of diseases like Alzheimer's," said Bruno, who was not involved in the study. "We haven't done any of the prostate cancer treatment with ultrasound as yet [at our institution], but we have purchased such a device and we will be starting this use soon. It is very promising."

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