Stereotactic body radiotherapy (SBRT) was superior to external beam radiotherapy (EBRT) for alleviating pain in cancer patients with spinal metastases, according to a study published in The Lancet Oncology.
In a phase 2/3, randomized trial (ClinicalTrials.gov Identifier: NCT02512965), researchers sought to determine whether SBRT could improve the complete response (CR) rate for pain at a specific site of spinal metastasis, compared with conventional EBRT.
The intention-to-treat analysis included 229 patients with painful, MRI-confirmed spinal metastases. They had a range of primary malignancies, including breast, lung, genitourinary, gastrointestinal, renal cell, and head and neck cancers, as well as melanoma and other cancers.
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Half of patients (n=114) were assigned to SBRT (24 Gy in 2 daily fractions), and the other half (n=115) were assigned to EBRT (20 Gy in 5 daily fractions).
The median follow-up was 6.7 months. The primary endpoint was the proportion of patients with a CR for pain at 3 months after radiotherapy.
At 3 months, the CR rate was 35% in the SBRT arm and 14% in the EBRT arm (risk ratio, 1.33; 95% CI, 1.14-1.55; P =.0002). This significant difference in CR was maintained in multivariable analyses (odds ratio, 3.47; 95% CI, 1.77-6.80; P =.0003).
At 3 months, the radiation site-specific, progression-free survival rate was 86% in the EBRT arm and 92% in the SBRT arm (P =.18). The overall survival rate at 3 months was 89% and 93%, respectively (P =.33).
The most common grade 3-4 adverse event was grade 3 pain that occurred in 4% of patients in the EBRT arm and 5% of those in the SBRT arm. There were no treatment-related fatalities.
“For patients with painful MRI-confirmed spinal metastases, in accordance with the eligibility criteria in this trial, spinal stereotactic body radiotherapy is to be considered a standard-of-care treatment option,” the study authors wrote.
“In patients with a life expectancy of less than 3 months and in those with other sites of metastatic disease, including non-spine bone metastases, use of standard conventional external beam radiotherapy (as applicable) should still be considered effective for symptom response,” they added.
Disclosures: This study was supported by the Canadian Cancer Society and the Australian National Health and Medical Research Council. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Reference
Sahgal A, Myrehaug SD, Siva S, et al. Stereotactic body radiotherapy versus conventional external beam radiotherapy in patients with painful spinal metastases: an open-label, multicentre, randomised, controlled, phase 2/3 trial. Lancet Oncol. 2021;22(7):1023-1033. doi:10.1016/S1470-2045(21)00196-0
