Analysing the suitability of tools used to assess cost-effectiveness of external beam radiation therapy – A scoping review

BACKGROUND: Cost-effectiveness analyses (CEAs) guide decision-making in radiotherapy. Despite CEAs impact on policy and resource allocation, limited evidence exists on the current tools and methods for external-beam radiotherapy (EBRT). This review aims to identify the suitability of CEA tools utilised in modern EBRT economic evaluations. METHODS: This scoping review followed Joanna Briggs Institute guidelines, with reporting aligned to the Preferred Reporting Items Systematic Reviews and Meta-analyses for Scoping Reviews. A systematic search of PubMed, Embase, and Scopus identified CEA studies on EBRT in adult populations. Data analysis focused on key CEA metrics, including inputs (transition probabilities, time horizons, cycle lengths, discounts, cost, patient factors), outputs (quality-adjusted life years, life-years gained, willingness-to-pay), and sensitivity analyses (deterministic and probabilistic). RESULTS: Of the 35 identified studies, 86% were model-based CEAs, with Markov being the most common approach. Model-based CEAs often failed to capture disease progression or adverse events adequately. Non-modelling studies relied on incremental cost-effectiveness ratios I(CER) calculations utilising retrospective clinical trial data. No standardised method for addressing missing data was identified. Palliative radiotherapy remains poorly represented, with only five CEA studies addressing it. POLICY SUMMARY: This review highlights significant methodological inconsistencies in radiotherapy CEAs, underscoring the need for a standardised approach tailored to EBRT. The breadth of methods and adaptations in conducting CEAs suggests that existing practices do not fully address radiotherapy needs. Despite emphasis on the importance of CEAs in radiotherapy, the evidence base offers little consensus.