Feb. 2 (UPI) -- An MRI-guided ultrasound treatment is effective against intermediate-risk prostate cancer and causes minimal side effects, according to a study published Tuesday by the journal Radiology.
Of 44 men who received the treatment, 41 were disease-free five months later, with little effect on erectile function and prostate symptoms, the data showed.
"By combining the high-intensity focused ultrasound device with MRI, we can target our treatment to the exact location because we're able to pinpoint precisely where the tumor is," study co-author Dr. Sangeet Ghai said in a press release.
"The results so far have been very good," said Ghai, a medical imaging specialist at the University Health Network Sinai Health and Women's College Hospital in Toronto.
"We treated a smaller area using this device, yet still had very good results, [while] ... the patients preserved their erectile and urinary function," he added.
Prostate cancer is the second most common cancer among men after non-melanoma skin cancer, with about 200,000 cases diagnosed in the United States each year, according to the American Cancer Society.
Current treatments such as surgery and radiation therapy that target the entire gland are effective at eliminating the cancer, but often cause incontinence and sexual dysfunction, Ghai and his colleagues said.
A new class of treatments called focal therapy, however, offers an alternative for some men with intermediate-risk disease that is confined to the prostate, the researchers said.
In high-intensity focused ultrasound therapy, the cancer is destroyed by heating the affected tissue by using a probe-like device called an ultrasound transducer, which focuses sound waves to generate heat at a single point.
In the past, the procedure has been performed using ultrasound, but ultrasound does show an image of the site of cancer within the prostate gland well enough to allow for good targeting. Magnetic resonance imaging improves that targeting.
Since the treatment is targeted at a small area within the prostate, side effects are generally less than those associated with surgery and radiation therapy, the researchers said.
For this study, they used a device that delivers MRI-guided focused ultrasound treatment via a probe placed in the rectum while the patient is under general anesthesia.
Results of the procedure, which takes about four hours, were tracked using MRI, biopsies and surveys of erectile and urinary function. Treatment was successfully completed in all the men, with no major side effects, the researchers said.
Using MRI allows thermal feedback during treatment, which is important because killing the cancerous tissue requires a temperature of more than 140 degrees Fahrenheit. The method also allows surgeons to see whether all the cancer has been eradicated, researchers said.
"MRI almost instantaneously gives feedback as to the temperature that we've been able to achieve at the site," Ghai said.
"If the temperature was not what I wanted to get, I can reheat that area so that chances for successful treatment increase," he said.
The treatment is pending approval by the U.S Food and Drug Administration and Health Canada.