The SMART Trial: A Randomised Feasibility Study Comparing Single Fraction and Multifraction Arc-Based Radiotherapy for Painful Bone Metastases
The SMART Trial: A Randomised Feasibility Study Comparing Single Fraction and Multifraction Arc-Based Radiotherapy for Painful Bone Metastases
This prospective randomised pilot feasibility study will compare single-fraction radiotherapy (8 Gy × 1) with multifraction radiotherapy (20 Gy in 5 fractions) for the palliation of painful bone metastases. The study will evaluate pain response at 4 weeks following radiotherapy, together with feasibility, treatment compliance, toxicity, pain flare, retreatment, patient convenience and resource utilisation. The study will generate preliminary data to inform the design of a future definitive randomised trial.
Single-fraction radiotherapy (SFRT) is an established standard treatment for palliation of painful bone metastases. However, multifraction radiotherapy (MFRT) continues to be widely used in clinical practice because of concerns regarding durability of pain control and retreatment. With the increasing use of modern arc-based radiotherapy techniques such as volumetric modulated arc therapy (VMAT), there is a need to evaluate whether single-fraction radiotherapy can provide effective pain palliation while reducing treatment burden and improving resource utilisation.
The SMART trial is a prospective, single-centre, randomised, open-label, parallel-group pilot feasibility study comparing VMAT-based SFRT (8 Gy in 1 fraction) with VMAT-based MFRT (20 Gy in 5 fractions) in patients with painful bone metastases, including spinal metastases.
Approximately 70 participants will be randomised in a 1:1 ratio to receive either SFRT or MFRT. Both treatment schedules will be delivered using VMAT with daily image-guided radiotherapy using cone-beam computed tomography (CBCT)-based image guidance.
Stratified block randomisation will be used according to the site of metastasis (spine versus non-spine) to maintain balance between the two treatment groups. Within each stratum, computer-generated variable block randomisation using block sizes of 4 and 6 will be used. Allocation will be concealed using sequentially numbered, opaque, sealed envelopes.
Pain will be assessed using the Numeric Rating Scale (NRS-11) and Wong-Baker FACES Pain Scale at baseline and during follow-up. Participants will be assessed at 2 weeks, 4 weeks and 12 weeks after radiotherapy.
The primary aim of this pilot study is to assess the feasibility of conducting a randomised controlled trial at the participating tertiary oncology centre. Feasibility will include recruitment, treatment completion, follow-up completion and completeness of study data.
The primary efficacy outcome will be overall pain response at 4 weeks following radiotherapy. Secondary outcomes will include pain response at other follow-up time points, retreatment rates, pain flare, treatment-related toxicity, patient convenience and resource utilisation.
The study is not powered to provide a definitive non-inferiority conclusion. A non-inferiority margin of 15% has been prespecified to guide estimation of the treatment effect and inform the design and sample size of a future definitive randomised trial. The primary efficacy analysis will compare overall pain response between the two treatment groups using the intention-to-treat population.
The study will generate preliminary feasibility and clinical outcome data to inform the design of a future definitive randomised controlled trial evaluating single-fraction versus multifraction radiotherapy for painful bone metastases.
Inclusion Criteria:
Exclusion Criteria:
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