Ambulation outcomes not quite noninferior with single vs multifraction radiotherapy
medwireNews: Researchers have been unable to show that single-dose radiotherapy is not inferior to multifraction radiotherapy in terms of ambulatory status in patients with metastatic prostate, lung, or breast cancer and spinal cord or cauda equina compression.
However, Peter Hoskin (Mount Vernon Cancer Centre, Northwood, UK) and team stress that the limited extent “to which the lower bound of the CI [confidence interval] overlapped with the noninferiority margin should be considered when interpreting the clinical importance of this finding.”
The SCORAD trial found that 69.3% of 166 patients who were randomly assigned to receive external beam single-fraction 8-Gy radiotherapy were ambulatory with or without the use of walking aids at 8 weeks, compared with 72.7% of the 176 patients assigned to receive 20 Gy of radiotherapy in five fractions over 5 consecutive days.
This gave a risk difference of –3.5%, with a lower confidence interval limit of –11.5%, which did not meet the predefined noninferiority margin of −11.0%.
But analysis of the differences at weeks 1, 4, and 12 found that the single-fraction regimen was non-inferior to the multifraction regimen. At these time points, the differences in the proportion of ambulatory patients were −0.4%, −0.7%, and 4.1%, respectively, with corresponding lower confidence limits of –6.9%, –8.1%, and –4.6%.
The researchers describe these differences as “small and unlikely to be of clinical importance.”
Furthermore, there was no significant difference in overall survival between the two groups at 12 weeks, with rates of 50% and 55% in the single-fraction and multifraction groups, respectively.
And there were also no differences between the groups in the remaining secondary endpoints, such as loss of ambulation in those ambulatory at baseline, return of ambulation in those non-ambulatory at baseline, additional treatments, quality of life including pain, and adverse events such as bladder and bowel functioning.
Although nonsignificant, the rate of bladder toxicity was higher in the single-fraction group than in the multifraction group, particularly when radiotherapy was given for cauda equina compression.
Hoskin et al therefore suggest that radiotherapy given in “5 fractions may be preferred for this subgroup.”
The study findings are published in JAMA.
By Laura Cowen
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