Background: Seven Genomic Medicines Service Alliances (GMSAs) have been established to deliver equitable patient access and embed genomics into routine care across England.1 Fluoropyrimidine SACT is frequently used for many cancers and metabolised by dihydropyrimidine dehydrogenase (DPD). DPYD gene variants can cause DPD deficiency, potentially leading to severe toxicity. In November 2020, NHSE/I recommended testing all patients for DPYD polymorphisms prior to the commencement of fluoropyrimidine SACT.2 As part of a national transformation project, led by the South East and North West GMSAs, a baseline survey was undertaken in June 2021 to gain an understanding of DPYD testing pathways. The invitation was extended across the UK to Scotland, Wales and Northern Ireland to obtain a national overview. Objective: To understand: - Degree of DPYD testing across the UK - Personnel & process involved in requesting, following up and actioning the result within the DPYD pathway. Methodology • South East GMSA collated data using SurveyMonkey as a data collection tool, on behalf of the National DPYD Oversight Group, as part of a wider baseline survey. • Following piloting the survey on four Trusts, the survey link was emailed to all Cancer Lead Clinicians, via the organisational Medical Director and Chief Pharmacist (or equivalent for home nations). Results: 220/222 (99%) organisations contacted across England, responded to the survey. 105 organisations confirmed they did not deliver fluoropyrimidine SACT; two organisations did not respond and were excluded from the analysis. 138 organisations (115 England, 23 home nations) confirmed delivery of fluoropyrimidine SACT and completed the full survey. 100% of organisations reported testing for DPYD, but not always all tumour types – the main tumour sites tested were breast, colorectal and upper-GI. Within England, 87% organisations reported sending tests to aGenomic LaboratoryHub(GLH).The averageUKturnaround time from sampling to reportingwas < 5 days for 42/ 138 (36%) and ≥ 6 days for the remaining organisations. 69% of UK organisations reported following UKCB Guidelines for dose adjustments.3 75/138 organisations delayed treatment until the result was reported and 60/ 138 organisations reported going ahead for the first cycle, according to local guidelines, if urgent. Discussion: DPYD testing has been widely implemented across the UK but not always equitably for all tumour sites. Tests are mainly requested by the consultant/registrar at the time of prescribing – this is not always the individual checking the result. In many organisations, DPYD result is checked by the screening pharmacist/SACT nurse/independent prescriber. For identified variants, dose adjustments are primarily made by the consultant/registrar; the screening pharmacist/independent prescriber may also dose adjust. Screening pharmacists play a pivotal role to ensure patients’ DPYD results are followed up and subsequent treatment is appropriately dosed. Follow-up of unavailable results is driven by the consultant/registrar/screening pharmacist. Next steps - Improve local awareness to ensure equitable DPYD testing across all tumour types for fluoropyrimidine SACT, including chemo-radiation. - Local collaboration with GMSA/GLHs to optimise pathways for DPYD testing. - Develop a gold standard pathway and update national guidance accordingly. [ABSTRACT FROM AUTHOR]