In a Canadian/Australian phase II/III trial reported in The Lancet Oncology, Arjun Sahgal, MD, and colleagues found that stereotactic body radiotherapy (SBRT) produced a higher complete pain response rate vs conventional external-beam radiotherapy (EBRT) in patients with painful spinal metastases.

Arjun Sahgal, MD

Study Details

In the open-label trial, 229 patients from sites in Canada and Australia were randomly assigned between January 2016 and September 2019 to receive SBRT (n = 114) or conventional EBRT (n = 115). Patients had painful metastases, defined as Brief Pain Inventory (BPI) score ≥ 2 points; three or fewer consecutive vertebral segments to be included in the treatment volume; a Spinal Instability Neoplasia Score < 12; and no neurologically symptomatic spinal cord or cauda equina compression. SBRT was given at a dose of 24 Gy in two consecutive daily fractions; EBRT was given at a dose of 20 Gy in five consecutive daily fractions. The primary endpoint was the proportion of patients with a complete response for pain at 3 months after radiotherapy in the intention-to-treat population, with complete response defined as worst pain score of 0 on the BPI with no associated increase in daily oral morphine-equivalent consumption.

Key Findings

Median follow-up was 6.7 months (interquartile range = 6.3–6.9 months).

At 3 months, complete pain response was observed in 40 (35%) of 114 patients in the SBRT group vs 16 (14%) of 115 patients in the conventional EBRT group (risk ratio [RR] = 1.33, 95% confidence interval [CI] = 1.14–1.55, P = .0002). The significant difference was maintained in multivariate analysis (odds ratio [OR] = 3.47, 95% CI = 1.77–6.80, P = .0003).

At 6-month assessment, 36 patients (32%) in the SBRT group and 39 (34%) in the EBRT group were not evaluable but were included in the intention-to-treat analysis. Complete pain response was observed in 37 (32%) vs 18 (16%) patients (RR = 1.24, 95% CI = 1.07–1.44, P = .0036). The significant difference was maintained in multivariate analysis (OR = 2.45, 95% CI = 1.28–4.71, P = .0070).

The most common grade 3 or 4 adverse event (> 1% of patients in either group) was grade 3 pain (5% of SBRT group vs 4% of EBRT group); the only reported grade 4 event was vertebral compression factor in one patient in the EBRT group. Vertebral compression fractures of any grade occurred in 11% vs 17% of patients; 30 of 32 events were grade 1. No treatment-related deaths were observed.

The investigators concluded, “SBRT at a dose of 24 Gy in two daily fractions was superior to conventional EBRT at a dose of 20 Gy in five daily fractions in improving the complete response rate for pain. These results suggest that use of conformal, image-guided, stereotactically dose-escalated radiotherapy is appropriate in the palliative setting for symptom control for selected patients with painful spinal metastases, and an increased awareness of the need for specialized and multidisciplinary involvement in the delivery of end-of-life care is needed.”

Dr. Sahgal, of the Odette Cancer Center, Sunnybrook Health Sciences Center, University of Toronto, is the corresponding author for The Lancet Oncology article.

Disclosure: The study was funded by the Canadian Cancer Society and Australian National Health and Medical Research Council. For full disclosures of the study authors, visit thelancet.com.