In a phase II trial reported in the Journal of Clinical Oncology, Erin F. Gillespie, MD, MPH, and colleagues found that prophylactic radiotherapy in patients with high-risk asymptomatic bone metastases from solid tumors reduced the risk of skeletal-related events compared with standard of care. A survival benefit was also observed.
Erin F. Gillespie, MD, MPH
Study Details
A total of 78 patients with 122 high-risk asymptomatic bone metastases receiving treatment at Memorial Sloan Kettering (MSK) Cancer Center and MSK Cancer Alliance partner sites were enrolled in the study between May 2018 and August 2021. Patients were randomly assigned to prophylactic radiotherapy (n = 39, 62 metastases) or standard of care (n = 39, 49 metastases).
Radiotherapy technique was selected by the treating radiation oncologist. Planned standard-of-care treatment consisted of systemic therapy (90% of patients) or observation (10%). The most common primary cancer types were lung (27%), breast (24%), and prostate (22%). The primary outcome measure was incidence of skeletal-related events at 1 year.
Key Findings
At 1 year, skeletal-related events had occurred in 1 (1.6%) of 62 bone metastases in the radiotherapy group vs 14 (29%) of 49 bone metastases in the standard-of-care group (P < .001). Skeletal-related events in the standard-of-care group included eight cases of palliative radiotherapy for pain, four pathologic fractures, and two spinal cord compressions. At 1 year, hospitalization for skeletal-related events had occurred in no patients in the radiotherapy group vs four in the standard-of-care group (P = .045).
At a median follow-up of 2.5 years (95% confidence interval [CI] = 1.9–3.2 years), median overall survival was 1.7 years (95% CI = 1.3 years to not reached) in the radiotherapy group vs 1.0 years (95% CI = 0.8–1.9 years) in the observation group (hazard ratio [HR] = 0.49, 95% CI = 0.27–0.89, P = .018); the benefit remained significant on multivariate analysis (HR = 0.46, 95% CI = 0.25–0.83, P = .01).
No grade ≥ 3 treatment-related adverse events occurred in the radiotherapy group. Treatment-related grade 1or 2 events occurred in 13% of patients in the radiotherapy group (including nausea in 3 patients) vs 3% in the standard-of-care group.
The investigators concluded, “Radiation delivered prophylactically to asymptomatic, high-risk bone metastases reduced skeletal-related events and hospitalizations. We also observed an improvement in overall survival with prophylactic radiation, although a confirmatory phase III trial is warranted.”
Dr. Gillespie, of the Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by grants from the National Cancer Institute. For full disclosures of the study authors, visit ascopubs.org.
