Prophylactic radiation therapy delivered to patients with high-risk asymptomatic bone metastases from cancer decreases the risk for skeletal-related events (SREs), hospitalization, and death, according to the findings of a phase 2 clinical trial that investigators believe is the first study of its kind.
In a phase 2 trial, a team led by Erin F. Gillespie, MD, MPH, of Memorial Sloan Kettering Cancer Center in New York, New York, enrolled 78 patients with 122 high-risk asymptomatic bone metastases, randomly assigning 39 patients to receive prophylactic radiation therapy and 39 patients to receive standard of care (SOC; systemic therapy or observation). Of the 78 patients, 7 withdrew from the trial or were lost to follow-up, leaving 36 patients with 49 bone metastases in the observation arm and 35 patients with 62 bone metastases in the radiation therapy arm. The most common primary cancer type was lung (27%), followed by breast (24%) and prostate (22%).
During 1 year of follow-up, 15 SREs developed: 14 among the 49 bone metastases in the SOC arm (29%) and 1 among the 62 metastases (1.6%) in the radiation therapy arm, a significant difference between the groups, Dr Gillespie and colleagues reported in the Journal of Clinical Oncology. The investigators defined SREs as the occurrence of pathologic fractures, spinal cord compression, orthopedic surgery to bone, and/or palliative radiation therapy for pain.
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In addition, within the first year of follow-up, a significantly smaller proportion of patients in the radiation therapy arm than the SOC arm was hospitalized (0% vs 11%).
At a median follow-up of 2.5 years, the radiation therapy group has significantly longer median survival compared with the SOC arm (1.7 vs 1.0 years).
“Given the multi-institutional nature of the study and large effect size for reducing SRE, these findings may support the consideration of RT for select patients with high-risk asymptomatic bone metastases in routine practice,” Dr Gillespie’s team concluded.
Reference
Gillespie EF, Yang JC, Mathis NJ, et al. Prophylactic radiation therapy versus standard of care for patients with high-risk asymptomatic bone metastases: A multicenter, randomized phase II clinical trial. J Clin Oncol. Published online September 25, 2023. doi:10.1200/JCO.23.00753