MRI-Guided Focused Ultrasound Eases Pain From Bone Metastases

MRI-guided focused ultrasound improved pain and quality of life for patients with bone metastases, similar to external beam radiation therapy (EBRT), according to a prospective nonrandomized phase II trial in Italy.

At 1-month follow-up, the overall response rates were 91% for those who underwent focused ultrasound and 67% for those who underwent EBRT (P<0.001), with complete response rates of 43% and 16%, respectively (P<0.001), reported Alessandro De Maio, MD, of Sapienza University of Rome, and colleagues.

The mean baseline Numeric Rating Scale (NRS) score — with 0 representing “no pain” and 10 representing “worst pain imaginable” — was 7.0 in the focused ultrasound group and 6.6 in the EBRT group (P=0.16), which dropped to 3.2 and 5.1, respectively, at 1 month (P<0.001), they noted in Radiology.

“On the basis of the evidence provided in our study, MRI-guided focused ultrasound may represent a valid alternative for specific anatomic sites (pelvis, sternum, and long bones, including the ribs),” De Maio and colleagues wrote. “However, in consideration of the inherent bias of a nonrandomized study and the potential unmeasured variables that can account for the apparent treatment effect, our conclusions point to the need for a randomized trial to further investigate such results.”

Pain relief was durable at 12 months in both groups of patients, with overall response rates of 92% in the focused ultrasound group and 61% in the EBRT group (P=0.003), with complete pain response in 74% and 35%, respectively (P=0.002), and partial response in 18% and 26%, respectively (P<0.001).

“Perhaps the future lies in combined therapies and hybrid techniques trying to bridge and exploit the advantages of each therapeutic approach,” suggested Alexis Kelekis, MD, PhD, of National and Kapodistrian University of Athens in Greece, in an accompanying editorial.

Of note, subtest analysis of QoL-Questionnaire Cancer-15 Palliative Care at each time point showed lower scores in the focused ultrasound group for physical function, appetite, nausea/vomiting, dyspnea, and overall perceived quality of life.

The overall adverse event rates were 15% in the focused ultrasound group and 24% in the EBRT group.

Kelekis noted that while one of the advantages of focused ultrasound is that it is a single-session treatment, it takes longer, and thus is more tiring for the patient, and also requires anesthesia, “which is technically more complicated with increased patient risk.”

“However, with its absence of ionizing radiation and better overall results when compared with radiation therapy, focused ultrasound is a promising alternative for the future,” he added.

The study, conducted from January 2017 to May 2019, included 198 participants, with 100 undergoing focused ultrasound (mean age 63, 51 women) and 98 undergoing EBRT (mean age 65, 52 women). All had painful bone metastases (excluding skull and vertebral bodies). The most common primary cancer sites were the prostate (40%) and breast (21%), while the most common sites of bone metastases were the pelvis (42%) and the femur (22%).

In this study, a complete response was defined as an NRS of 0 with no concomitant increase in analgesic intake and stable or reduced oral morphine equivalent dose. A partial response was defined as a reduction in NRS of two or more points from baseline without an analgesic increase or an analgesic reduction of at least 25% from baseline without an increase in pain.