Speaking up, stepping back: Expertise, authority and the social negotiation of overdiagnosis

The National Health Service Breast Screening Programme (NHSBSP) is a widely promoted public health intervention yet debates around overdiagnosis continue to shape discussions of its value. While prior research has examined health professional perspectives on breast screening, less is known about how those with healthcare related occupations mobilise and adjust their knowledge of overdiagnosis in different interactional contexts. This article draws on semi-structured interviews with twenty women who declined breast screening and/or breast cancer treatment following invitation to the NHSBSP. Most participants had health-related occupations, including general practitioners, medical writers, and patient advocates. Participants often drew on scientific literature to inform their decisions, with understandings of overdiagnosis and overtreatment playing a central role. This article examines how participants mobilised their expertise across different interactional contexts. Participants possessed significant expertise, but varied how much authority they claimed across interactions, so that knowledge and status were mobilised differently depending on context. In policy contexts, they challenged dominant narratives by raising concerns with those responsible for programme delivery and sharing alternative evidence. When interacting with clinicians, they adopted an authoritative stance, using their knowledge to contest prevailing assumptions about screening. In contrast, when engaging with lay audiences, they constrained their authority, signposting others to evidence rather than seeking to direct their decisions. These findings highlight that expertise and authority, are relational, shaped by audience reception, institutional recognition, and speakers' strategic restraint in how overdiagnosis is negotiated across policy, professional, and everyday settings.