A prospective phase II trial presented at the ASTRO meeting in Boston suggests that ultralow-dose radiation therapy can effectively control bone pain from multiple myeloma without the marrow toxicity of standard regimens. Investigators randomized 69 patients to either a single 4-Gy dose or two 2-Gy fractions, far below the usual 30 Gy in 10 fractions. At 4 weeks, 66% of evaluable patients had a complete or partial pain response, and by 6 months that figure rose to 86%.
Treatment was well tolerated: only five patients experienced adverse events, none reaching grade 3 or higher, and no treatment interruptions were needed. Bone marrow status was preserved, which the researchers say is critical for patients who may need chemotherapy, stem-cell transplant, or CAR T-cell therapy later. Only 19% of patients required re-irradiation, and those who did still had a 69% pain response rate.
Lead investigator Leslie Ballas of Cedars-Sinai argued that the data are strong enough for clinical adoption, noting that prior evidence was mostly retrospective. An ASTRO discussant, Chelsea Pinnix of MD Anderson, called the results exciting and said they may encourage earlier use of radiotherapy for myeloma patients with painful bone disease. The study's single-arm design and modest sample size mean confirmatory trials could still add confidence, but the authors believe the approach is ready for practice.