Magnetic resonance-guided focused ultrasound accelerates pain relief in painful bone metastasis
Magnetic resonance-guided focused ultrasound (MRgFUS) has comparable overall treatment response rate with conventional radiotherapy (RRT) but produces faster pain relief, a new matched-pair study shows.
“[W]e compared the clinical outcomes of MRgFUS with those of conventional RT as the first-line treatment for patients with painful bone metastasis. The results showed that both MRgFUS and RT, which provided response rates of >70 percent at the 3-month follow-up evaluation, were effective,” said researchers, adding that MRgFUS was more efficient in terms of the time course of pain palliation.
The study included 63 patients with painful bone metastasis, of whom 21 (median age 59 years; 52 percent male) received MRgFUS. An age-, sex- and primary cancer-matched control group of 42 patients (median age 63 years; 52 percent male) received conventional RT.
After a follow-up period of at least 3 months, patients who received MRgFUS and RT had no significant difference in mean numerical rating scale (NRS) pain scores (6.57±1.62 vs 6.21±1.61, respectively; p=0.4186). [J Bone Joint Surg Am 2017;99:1572-1578]
When changes in NRS scores over time were compared, patients who received MRgFUS had significantly lower scores at 1 week (2.5 vs 4.8; p<0.0001), 2 weeks (2.1 vs 3.6; p=0.0188) and 3 months (1.0 vs 2.3; p=0.0269). In contrast, scores at 1 month (2.0 vs 2.8; p=0.1849) and 2 months (1.7 vs 2.2; p=0.3509) did not differ between the MRgFUS and RT groups, respectively.
In terms of treatment response, MRgFUS patients reported significantly higher rates compared to RT counterparts at week 1 (71 vs 26 percent; p=0.0009) after treatment. During the second week, the significant interaction was attenuated, but the rates remained numerically higher in the MRgFUS group (76 vs 50 percent; p=0.06).
There were no further significant differences in treatment response rate. “Throughout the follow-up period, the rate of responders was higher in the MRgFUS-treated group than in the RT-treated group; however, the difference was not statistically significant after 1 week,” said researchers.
Because of improvements in pain relief and response rates, MRgFUS has recently been considered as a viable alternative to RT in treating painful bone metastasis. The treatment alternative is also available for use in patients with radioresistance.
Despite its utility, the new MEgFUS approach has important limitations, chief of which is its potentially destructive effects on tissues surrounding the tumour or site of metastasis.
“[T]he application of MRgFUS is constrained by its ablative nature and device-related restrictions, which exclude the skull, most of the spine and lesions that are not at least 1 cm away from tissues at risk,” said researchers.