Stereotactic radiosurgery did not outperform conventional external beam radiotherapy in patients with localized vertebral metastatic lesions

1. Pain response at 3 months post-treatment show no advantage of stereotactic radiosurgery vs. conventional external beam radiotherapy

2. Adverse events were similar between treatment groups

Evidence Rating Level: 1 (Excellent)

Study Rundown: Pain from vertebral metastatic lesions is commonplace in patients with advanced cancer. Conventional external beam radiotherapy (cEBRT) has historically been used for lesions that are not appropriate for surgical resection. Results from previous studies imply that stereotactic radiosurgery (SRS) may outperform cEBRT for pain relief and local tumour control.

This study examined whether treatment with SRS provided greater patient-reported pain relief compared to cEBRT. The primary outcome of this study was a patient reported pain score out of 10 (on the Numerical Rating Pain Scale (NRPS)) 3 months post-treatment. A pain level of 0 was considered a ‘complete response’, whereas improvement of the pain score by at least 3 points was considered a ‘partial response’. A ‘stable response’ was no improvement or within 2 points of the original pain score. Secondary outcomes were the duration and rapidity of the response to treatment, survival at 12 and 24 months, as well as adverse events (AE). Pain response results at 3 months post-treatment with SRS showed no advantage over cEBRT. At 12 months post-treatment, SRS pain response improved while the response to cEBRT had plateaued, but this result was insignificant. Survival rates for the SRS group were 44.3% at 12 months and 31.5% at 24 months. In the cEBRT group, the survival rates were 53.1% and 31.5%, respectively. AEs were similar between groups, with no differences at 3 months or beyond. Limitations to this study include low patient adherence to pain reporting (less than half of patients at 12 months provided NRPS scores and less than 1/3 provided scores at 24 months), which could contribute to a bias in pain response interpretation. Additionally, there was a significantly higher proportion of patients in the SRS group with a functional status of Zubrod level 2; these patients had lower NRPS reporting adherence than patients with a greater functional status (Zubrod 0 to 1), contributing to an imbalance between groups. This study excluded patients with vertebral compression fractures sustaining a greater than 50% height loss or having bony retropulsion, so the results should be applied conservatively in this demographic of patients. Overall, the results from this study suggest that SRS is not a superior treatment compared with cEBRT in the management of vertebral metastatic lesions.

Click to read the study in JAMA Oncology

Relevant Reading: Stereotactic body radiotherapy versus conventional external beam radiotherapy in patients with painful spinal metastases: an open-label, multicentre, randomised, controlled, phase 2/3 trial.

In-Depth [randomized controlled trial]: This non-blinded, randomized controlled trial study randomly assorted 339 adult patients with a minimum pain score of 5/10 on the NRPS in a 2:1 fashion to receive either SRS or cEBRT. Stratification was based on metastatic tumour load, SRS target dose (16 Gy vs. 18 Gy), and whether the cancers were radioresistant. At 3 months post-treatment, there was no evidence of an advantage of SRS vs. cEBRT with a between-group difference score of -19% points (95% confidence interval (CI), -32.9 to -5.5), suggesting a worse pain response in the SRS group. There was no difference in the mean change from the baseline of pain in either group at 3 months (SRS: -2.98 [3.34] vs. cEBRT: -3.83 [2.97]). While the post-SRS treatment pain response had improved at 12 months compared to the plateaued pain response to cEBRT in the same period, the difference was insignificant (57.6% vs. 55.5%, respectively). At 12 months post-treatment, survival rates for the SRS group were 44.3% and 31.5% at 24 months. Survival rates in the cEBRT group were 53.1% and 31.5%, respectively (hazard ratio [HR], 0.91; 95% CI, 0.69-1.20). AEs were not different between treatment groups, with 7.7% of all patients in either group having any AE at 3 months, 5.6% of patients in the SRS group, and 3.4% of patients in the cEBRT group having late effects. No patients reported spinal cord complications from either treatment modality.

Image: PD

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