BOSTON -- A short course of ultra-low-dose radiation therapy relieved painful bone lesions in most patients with multiple myeloma, according to a study presented at the American Society for Radiation Oncology (ASTRO) annual meeting. 

The results may help clinicians consider radiotherapy earlier in the course of care for patients with the disease, noted principal investigator Leslie Ballas, MD, of Cedars-Sinai in Los Angeles. 

“Because this approach is brief and uses a lower dose, it may make clinicians more comfortable referring patients earlier, so their patients don’t have to live with pain while waiting for other treatments to work,” Ballas said, in a September 27 news release from ASTRO. 

Radiation therapy (RT) is commonly used to relieve painful lesions, but patients often are referred later in their care after symptoms worsen, in part due to concerns about effects on healthy bone marrow or the logistics of coordinating radiation treatment with systemic therapy. 

To address the issue, Ballas and colleagues enrolled 63 patients with painful, uncomplicated myeloma bone lesions in a phase II trial at seven institutions from April 2019 to September 2025. Participants received 4 Gy of external beam RT as either a single 4 Gy fraction or two 2 Gy fractions. The primary outcome was patient-reported pain response at four weeks, assessed using Brief Pain Inventory (BPI) scores and oral morphine equivalent dosing (OMED). Patients with inadequate relief could receive reirradiation starting at four weeks. 

The median baseline BPI was 4.8 and the median follow-up after RT was 186 days. The pain response rate was 59% at four weeks (median BPI decrease, 2.25; median OMED decrease, 5 mg) and 63% at eight weeks (median BPI decrease, 2.75; median OMED decrease, 6.2 mg), with pain response of 82% at six months. The median time to pain relief was 36 days with a median duration of 148 days. There was no difference in pain relief based on fractionation. 

In addition, 24% of patients received a second course of RT, with a median dose of 20 Gy at a median of 71 days after completion of the 4 Gy treatment. Following reirradiation, the pain response rate was 63% after four weeks with a median time to pain relief of 95 days. 

"Even though this is a relatively small study, we now have prospective data from multiple institutions showing that this approach can provide meaningful pain relief with minimal side effects, making it a practical and flexible strategy for routine clinical care," Ballas said. 

She added that next steps include determining whether some patients with multiple myeloma might benefit from low-dose radiation therapy earlier in the course of bone disease, before pain becomes severe, and identifying which lesions are most likely to respond to this approach. 

Check out AuntMinnie’s full coverage of ASTRO 2026 on our ShowCast.