Establishing consensus on defining the physically vulnerable child with cancer: a protocol for an international Delphi approach.

Introduction: Childhood cancer survivors have an increased risk of lifetime morbidity and mortality. To improve outcomes, the physical impact of treatment toxicity must be minimised in the acute phase. Using a framework to identify early signs of physical vulnerability could provide an avenue for early intervention. Yet, existing models of physical vulnerability (sarcopenia and frailty) are adult-based definitions and require adaptation as they do not reflect the unique pathophysiology of paediatric cancer. Using phenotypes of sarcopenia and frailty as base, this study aims to establish a consensus definition of the physically vulnerable child with cancer.

Methods and analysis: A Delphi consensus approach is guided by a project team of four specialised oncology healthcare professionals. Five stages include defining the problem area, selecting panel members, conducting four Delphi rounds, establishing closing criteria and validation of results. A focus group of international experts will meet to define the problem area, in addition to a scoping review to collate existing definitions and assessments of sarcopenia and frailty within paediatric contexts. Delphi panel members will include multinational clinicians with >5 years' experience in the acute paediatric setting, and researchers specialising in sarcopenia and/or frailty in paediatric cancer. Delphi rounds will aim to achieve consensus on how to define physical vulnerability in children with cancer. Consensus will be considered achieved when 80% or more of panellists agree. A series of focus groups with select members of the Delphi panel, and families, children, and adolescents affected by paediatric cancer will be held to validate results.

Ethics and dissemination: The study has ethics approval through the Royal Children's Hospital Human Ethics Committee (number 3707). Results from this study will be published in peer-reviewed academic journals and disseminated via scientific conference(s) and key stakeholders.