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Single-fraction stereotactic body radiotherapy appears effective for bone metastases pain relief
Patients with painful bone metastases demonstrated higher rates of pain response with high-dose, single-fraction stereotactic body radiotherapy compared with standard multifraction radiotherapy, according to results of a randomized, phase 2 study published in Journal of Clinical Oncology.
“Despite numerous prospective randomized clinical trials, consensus has not been reached regarding the optimal radiation dose and fractionation for palliation of painful bone metastases,” Quynh-Nhu Nguyen, MD, associate professor in the division of radiation oncology at The University of Texas MD Anderson Cancer Center, and colleagues wrote. “Since the early 1980s, several trials have shown that palliative radiation, delivered in single or multiple fractions, can produce equivalent pain relief, but the single-fraction regimens generally led to higher retreatment rates.”
The nonblinded, single-institution, phase 2 noninferiority trial by Nguyen and colleagues included 160 patients (median age, 62.4 years; standard deviation, 10.4 years; n = 96 men) with painful bone metastases enrolled at a tertiary care center between Sept. 19, 2014 and June 19, 2018.
The researchers randomly assigned patients to undergo single-fraction SBRT (12 Gy for lesions 4 cm or larger and 16 Gy for lesions smaller than 4 cm; n = 81) or standard multifraction radiotherapy (MFRT) of 30 Gy in 10 fractions (n = 79). Groups appeared balanced in terms of sex, age, ethnicity, tumor histology, sites of bony metastases, pain scores at baseline, number of sites irradiated and Karnofsky performance status.
Pain response, defined by international consensus criteria as a composite of pain score and analgesic use (daily morphine-equivalent dose), served as the primary endpoint. The researchers defined pain failure as worsening pain score (increase of two points or more on a scale of 0 to 10), increase in morphine-equivalent opioid dose of 50% or more, repeat irradiation or radiographic evidence of disease progression, or pathologic fracture.
Results of the per-protocol analysis showed a higher proportion of pain responders (complete response plus partial response) in the SBRT group compared with the MFRT group at 2 weeks (62% vs. 36%; P = .01), 3 months (72% vs. 49%; P= .03) and 9 months (77% vs. 46%; P = .03). The researchers observed no differences in treatment-related toxicities or quality-of-life scores after the treatments.
Patients who received single-fraction SBRT showed higher rates of local control at 1 and 2 years compared with those who received MFRT. Median OS appeared similar between groups in the intent-to-treat analysis (6.7 months; range, 0.1-36.3), but was significantly higher for the SBRT group in a quality of life-adjusted OS analysis.
The high risks for death associated with metastatic cancer and variety of primary cancer types among patients in the study may have influenced the results, researchers noted in citing study limitations.
However, the findings mirror those of previous studies showing pain relief rates of 80% with SBRT among patients with spinal metastases.
“These findings represent the first prospective, randomized evidence to suggest that SBRT should be the standard of care for patients with excellent performance status, longer life expectancy and limited bone metastases,” the researchers wrote. “We recommend that higher single-fraction SBRT doses be further tested in larger phase 3 studies to validate our findings.” – by Jennifer Byrne
Disclosures: Nguyen reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.