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Original Articles: BiGART 2023 Issue

Interim analysis of patient-reported outcome compliance and dosimetry in a phase 3 randomized clinical trial of oesophagus-sparing spinal radiotherapy

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Pages 1496-1501 | Received 23 May 2023, Accepted 14 Aug 2023, Published online: 30 Aug 2023
 

Abstract

Background

The randomized clinical trial ESO-SPARE investigates if oesophagus-sparing radiotherapy (RT) can reduce dysphagia in patients with metastatic spinal cord compression (MSCC). Patient-reported outcome (PRO) is the only follow-up measure. Due to the fragile patient population, low respondent compliance was anticipated. We performed a planned interim analysis of dosimetry and respondent compliance, to ensure that the protocol requirements were met.

Methods

Patients >18 years referred for cervical/thoracic MSCC radiotherapy in 1-10 fractions were included from two centres. Patients were randomized (1:1) to standard RT or oesophagus-sparing RT, where predefined oesophageal dose constraints were prioritized over target coverage. Patients completed a trial diary with daily reports of dysphagia for 5 weeks (PRO-CTC-AE) and weekly quality of life reports for 9 weeks (QLQ-C30, EQ-5D-5L). According to power calculation, 124 patients are needed for primary endpoint analysis. The sample size was inflated to 200 patients to account for the fragile patient population. The co-primary endpoints, peak patient-reported dysphagia, and preserved ability to walk (EQ-5D-5L), are analysed at 5 and 9 weeks, respectively. The interim analysis was conducted 90 days after the inclusion of patient no 100. Respondent compliance was assessed at 5 and 9 weeks. In all RT plans, oesophagus and target doses were evaluated regarding adherence to protocol constraints.

Results

From May 2021 to November 2022, 100 patients were included. Fifty-two were randomized to oesophagus-sparing RT. In 23% of these plans, oesophagus constraints were violated. Overall, the dose to both target and oesophagus was significantly lower in the oesophagus-sparing plans. Only 51% and 41% of the patients were evaluable for co-primary endpoint analysis at five and nine weeks, respectively. Mortality and hospitalization rates were significantly larger in patients who completed <4 days PRO questionnaires.

Conclusion

Compliance was lower than anticipated and interventions to maintain study power are needed.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author, AMN, upon reasonable request, after the termination of the ESO-SPARE trial.

Additional information

Funding

The ESO-SPARE trial is supported by research grants from The Danish Cancer Society (grant no. R269-A15989), Varian Medical Systems, The Research Council at Copenhagen University Hospital Herlev and Gentofte, as well as DCCC Radiotherapy - The Danish National Research Centre for Radiotherapy, Danish Cancer Society (grant no. R191-A11526) and The Danish Comprehensive Cancer Centre. The results presented in this study were not associated with the funding sources.
The ESO-SPARE trial is supported by research grants from The Danish Cancer Society (grant no. R269-A15989), Varian Medical Systems, The Research Council at Copenhagen University Hospital Herlev and Gentofte, as well as DCCC Radiotherapy - The Danish National Research Centre for Radiotherapy, Danish Cancer Society (grant no. R191-A11526) and The Danish Comprehensive Cancer Centre. The results presented in this study were not associated with the funding sources.

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