Ultrasound News: Calibrated Therapy
By Dave Yeager
Radiology Today
Vol. 20 No. 4 P. 28

According to the Centers for Disease Control and Prevention, prostate cancer is the second most common cancer in men in the United States. It is also the second deadliest cancer among US men. Because prostate cancers vary in aggressiveness, treatment options range from active surveillance to complete removal of the gland.

Some common prostate cancer treatments can have unpleasant side effects, such as incontinence and loss of sexual function. A newer treatment, high-intensity focused ultrasound (HIFU), is showing promise for treating men with localized disease while minimizing side effects. The treatment uses focused ultrasound waves to ablate cancerous lesions with HIFU. Although the technology has been available in Europe for 20 years, treatment has been focused on the entire prostate gland, rather than specific lesions, says Bruno Nahar, MD, an assistant professor of urologic oncology at the University of Miami Miller School of Medicine. Now, focal ablation, which targets only the diseased part of the prostate, is being offered to selected patients.

HIFU was FDA approved for use in prostate tissue in October 2015, and the first institutional review board-approved prospective nonsalvage study in the United States was begun in January 2016. Nahar, the trial’s lead researcher, says 70 patients have been treated so far. The median follow-up is two years, and patients with locally advanced or metastatic disease are not eligible; the cancer must be localized and on only one side of the prostate. Any Gleason grade is considered, but low volume/low risk and high volume/high risk patients are excluded from the study. Patients are followed with prostate-specific antigen (PSA) tests every three months and undergo a biopsy at six or 12 months, depending on whether their disease is classified as high risk or low/intermediate risk, respectively.

“We use biopsy results to determine the efficacy and success of the treatment, and we saw that about 85% of these patients have a negative biopsy in the ablated area. They all get an MRI before the biopsy because, if there are any suspicious spots seen on the MRI, we can still target them. While 15% of them had either residual tumor or recurrence, 85% were cancer-free,” Nahar says. “These are early, short-term results. We still need long-term results, but it’s very promising.”

Who Benefits?
Not all patients will benefit from HIFU ablation. Edward M. Uchio, MD, director of urologic oncology at UCI Health in Orange County, California, says the stage of the cancer and its biological characteristics are important considerations.

“The majority of cancers probably should undergo active surveillance, but certain patients aren’t comfortable with that. And, also, some of these tumors have characteristics that appear to be slightly more aggressive and may give a patient a problem in the future,” Uchio says. “So we try to treat it while it’s very small. And the reason we do focal therapy is the side effects are very favorable compared to treating the whole prostate.”

Uchio has been treating patients with HIFU for a decade. He has worked on several trials, including the STAR Trial, which helped get HIFU approved in the United States. He says patients must meet specific criteria to be considered for the procedure.

“For focal therapy, I look for very isolated, lower-risk tumors, confined to one side of the prostate, that are not at high risk for having significant cancer on the other side or outside the prostate,” Uchio says. “So we can do focal therapy, where we can treat just the part of the prostate containing cancer, rather than treating the whole gland.”

MR images are acquired to target the tumors and guide treatment.

“We acquire multiparametric prostate MRI using standard protocols, basically with a 3 T magnet. We don’t use an endorectal coil, and, afterward, we identify lesions that are PI-RADS 3 and above. These lesions and the prostate get segmented on a separate software, and then that software is utilized for fusion transrectal imaging for biopsy,” says Roozbeh Houshyar, MD, director of abdominal MRI at UCI Health. “The fusion data also can be utilized for the HIFU. The prostate is segmented, and so are the lesions.”

Delivering the treatment requires cooperation between radiology, urology, and pathology. Houshyar says workflows need to be harmonized to provide optimal care.

“We have our workflow set up so we can do this. It takes a lot of collaboration between our departments,” Houshyar says. “We work very closely together to make sure the patient care is smooth.”

Nahar reports positive results for functional outcomes, so far. He says patients tend to experience some urinary symptoms immediately after the procedure, but they generally return to their baseline function within three months. He has yet to have a patient with urinary incontinence one year post procedure, and approximately 85% of patients have preserved their sexual function. Additionally, 80% of patients’ PSA scores dropped below 2 at three months’ follow-up. Nahar notes, however, that patients who have moderate to severe urinary symptoms at the outset tend to experience more side effects.

“We have to wait for long-term data in order to determine the true role for HIFU in the treatment of patients with prostate cancer,” Nahar says. “I think we have very good early outcomes, promising results but, still, these data—ours and other institutions’—do need to mature a little bit.”

— Dave Yeager is the editor of Radiology Today.