739eP Thinking through less: Understanding attitudes toward de-escalation and their impact on recruitment to breast cancer trials

Background: As outcomes in breast cancer continue to improve, treatment deescalation is increasingly explored to reduce overtreatment and unnecessary toxicity while maintaining survival.However, reducing treatment intensity often challenges clinical norms and patient expectations, making de-escalation trials difficult to recruit to.Participation decisions require individuals to think through less treatment in a context where "more" has traditionally been associated with safer and more effective.In breast cancer de-escalation trials, healthcare professionals play a key role in recruitment through clinical recommendations and risk communication.They perception of equipoise, responsibility and concern about recurrence may influence whether and how trials are offered, shaping patients' opportunities to participate.This synthesis explores patients' experiences of participation and HCP's perspectives on recruitment to identify key barriers and facilitators.Methods: A qualitative evidence synthesis examined HCP and patient perspectives on recruitment to and participation in breast cancer de-escalation trials.Using the SPIDER framework, systematic searches were conducted in PubMed, PsycINFO, CINAHL, Scopus, EMBASE, and the Cochrane Library.Eligible qualitative and mixed-methods studies were synthesised using inductive thematic analysis, followed by deductive mapping to the TDF to identify behavioural determinants.Study quality was appraised using CASP and confidence in findings will be assessed using GRADE-CERQual.Results: Emerging findings from the ongoing synthesis indicate that recruitment to de-escalation trials is shaped by emotional, ethical and informational factors.Patients report concerns about reduced treatment intensity and uncertainty about efficacy, while healthcare professionals highlight challenges around risk communication, equipoise and patient safety.Conclusions: Recruitment to breast cancer de-escalation trials is shaped by psychosocial and contextual factors.Understanding these influences can inform recruitment strategies that better reflect patient priorities and clinician perspectives, supporting improved trial acceptability and recruitment.