Need for and design of a trial to test efficacy of weight loss interventions for cancer prevention: an international consensus using expert nominal group and Delphi methods.

Obesity is associated with increased risk of at least 13 cancer types. Evidence from bariatric surgery cohorts and some behavioural intervention trials supports the notion that weight loss can prevent obesity-related cancers. The introduction of glucagon-like peptide (GLP)-1 agonist drugs has rapidly revolutionised pharmacotherapy options. A cancer prevention clinical trial would be complex, lengthy, and costly; therefore, we undertook an international expert consensus to assess the need for and design of a weight-loss intervention cancer prevention trial. We used a combination of two nominal group meetings, sandwiching 3 Delphi rounds. A panel of 54 international, multi-disciplinary researchers was established, informed by patient groups. Feedback was incorporated iteratively, and borderline statements, those that did not reach consensus, were addressed in a final meeting. Through the Delphi rounds, retention rates were high (98%, 85%, 88%). Consensus was achieved on 25 statements. Including: (i) there is a need for clinical trial evidence to inform obesity-related cancer prevention strategies; (ii) a trial should reflect high-risk populations; (iii) trials should prioritise GLP-1 agonists; and (iv) future research should explore mechanistic pathways and relevant cancer precursors. This consensus underscores the need for trial evidence to inform strategies for obesity-related cancer prevention.