Multifraction radiotherapy provides slightly better ambulatory status among patients with spinal-canal compression from metastatic cancer, compared with single-fraction radiotherapy, according to findings from the SCORAD noninferiority trial.
Most patients with spinal-canal compression due to metastatic cancer are treated with radiotherapy, and common practice has been to deliver 20 to 30 Gy in five to 10 fractions. One systematic review on spinal-canal compression reported similar outcomes between single-fraction and multifraction radiotherapy.
Dr. Peter J. Hoskin from Mount Vernon Cancer Center, in Northwood, U.K., and colleagues from 42 U.K. and five Australian sites compared the two approaches in a randomized trial of 686 patients.
Only 166 patients in the single-fraction group and 176 patients in the multifraction group completed the eight-week assessment and were included in the intention-to-treat analysis.
At week 8, ambulatory status grade 1 (ambulatory without the use of walking aids and grade 5/5 muscle power in all muscle groups) or 2 (ambulatory with assistance of walking aids or grade 4/5 muscle power in any muscle group) was achieved by 69.3% of patients in the single-fraction group versus 72.7% of patients in the multifraction group, a difference that fell just short of noninferiority.
The secondary ambulatory response rates at weeks 1, 4 and 12, however, did not differ significantly between the treatment groups and met noninferiority criteria, the researchers report in the December 3 issue of JAMA.
Among patients with ambulatory status 1 or 2 at baseline, there was no significant difference between the groups in the time to loss of ambulation. The same was true of patients with ambulatory status 3 (unable to walk with no worse than grade 2/5 power in all muscle groups or grade 2/5 power in any muscle group) or 4 (absence or flicker of motor power in any muscle group) at baseline.
The groups did not differ significantly in 12-week or 12-month survival or in the percentage of patients with grade-3 or -4 adverse events. But the rates of grade-1 or -2 radiation reactions were lower in the single-fraction group (11.6%) than in the multifraction group (19.4%).
"In this international noninferiority trial involving patients with metastatic spinal canal compression, treatment with single-fraction radiotherapy, compared with multifraction radiotherapy, did not meet the criterion for noninferiority for achieving ambulatory response status grade 1 or 2 at 8 weeks," the researchers note. "The lower bound of the 95% confidence interval (CI) (-11.5%) overlapped the noninferiority margin of -11%."
"However, for all other time points, the CI limits were within the noninferiority margin, and the observed risk differences between single-fraction and multifraction radiotherapy groups in ambulatory status were small and unlikely to be of clinical importance," they write.
"The extent to which the lower bound of the CI overlapped with the noninferiority margin should be considered when interpreting the clinical importance of this finding," the authors concludeDr. Mai Anh Huynh of Brigham and Women's Hospital, in Boston, who recently reviewed palliative radiotherapy for vertebral metastases and metastatic cord compression in patients treated with anti-PD-1 therapy, told Reuters Health by email, "It was most surprising to see results suggesting similar efficacy between single-fraction and multifraction treatment by most clinical outcomes assessed. Though this narrowly missed their prespecified margin for noninferiority, the similar outcomes for single- and multifraction treatment for spinal cord compression do suggest that the two regimens may be more comparable than we think."
"For patients with limited life expectancy and particularly those represented among this study population (i.e., predominantly elderly men with prostate cancer, not surgical candidates), single-fraction radiotherapy should be considered," said Dr. Huynh, who was not involved in the study. "These findings highlight the high risk of death for patients presenting with cord compression, with a median survival of only 3 months, where single-fraction treatment may offer the best value to patients as far as promoting and preserving their quality of life."
"These findings should help clinicians counsel patients about expected outcomes after radiotherapy and encourage adoption of single-fraction treatment, which may be similarly effective for patients with spinal cord compression but may be associated with a higher risk of symptomatic progression for patients with compression of the cauda equina," she said.
Dr. Anish Butala of the University of Pennsylvania Perelman School of Medicine, in Philadelphia, who recently reviewed radiotherapy treatment options in complex palliative settings, echoed this sentiment, noting, "Given the limited life expectancies associated with spinal-cord compression, it would not be unreasonable to deliver single-fraction radiotherapy after taking into account patient prognosis, goals, values, and priorities."
"While the trial is statistically negative, the absolute numbers are quite similar and suggest noninferiority of the single-fraction arm at 1, 4, and 12 weeks," he told Reuters Health by email. "This is a point that is worth at least discussing with patients who have spinal-cord compression and limited life expectancy."
"The trial excluded those with hematologic malignancies and those with prior radiation therapy to the spine, so the findings are not generalizable to these populations," said Dr. Butala, who also was not part of the study.
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