"I'm quite proud of how we've handled it": health professionals' experiences of returning additional findings from the 100,000 genomes project.

Participants in the 100,000 Genomes Project (100kGP) could consent to receive additional finding (AF) results, individual variants relating to genes associated with susceptibility to cancer and familial hypercholesterolemia (FH). In the study reported here, qualitative interviews were used to explore the experiences of National Health Service (NHS) professionals from across England who were tasked with returning over 80,000 "no AF" results and 700 positive AF results to 100kGP participants. Interviews were conducted with 45 professionals from a range of backgrounds, including Genetic Counsellors, Clinical Geneticists, FH Clinical Nurse Specialists and Clinical Scientists. Interviews were analysed using a codebook thematic analysis approach. Returning AF results has been a significant endeavour, with challenges for pathways, administrative processes and clinical and laboratory time when the capacity of NHS services is already stretched. Professionals discussed going "above and beyond" to prioritise patient care through pathway design, additional clinics, overtime, longer appointments and provision of follow-up appointments. Professionals also described facing practical and emotional challenges when returning AFs. Benefits for patients from receiving AFs in the 100kGP were highlighted and professionals were generally positive about offering clinically actionable AFs within routine NHS clinical care. Professionals were, however, cautious around the implementation of AFs into routine care and felt more research and discussion was needed to determine which AFs to offer, approaches to consent and communication of results, costs and the potential strain on NHS capacity and resources. Further consultation is required with careful review of pathways and resources before offering AFs in clinical practice.