In line with this recommendation the UK Chemotherapy Board (which includes UKONS representation) has published guidance which should be put in place in order to reduce the risk of severe adverse events when using fluoropyrimidines.
The guidance stipulates that all patients due to receive fluoropyrimidine based therapy, should have a DPD test prior to starting treatment.
Any patient who has not had a DPD test should be discussed with the consultant prior to going ahead. In exceptional circumstances where an agreement is made from the consultant that the patient can go ahead without a DPD test, the consultant or pharmacist must document clearly both in the chemotherapy prescribing system and, in the patient’s medical record.
Each organisation should ensure there is a clear process for requesting a DPD test. Details of the local testing facility should be available and working with the laboratory a turnaround time of <5 days should be aimed for.
The DPD Deficiency test determines whether the patient has polymorphisms of the DPYD gene which produces DPD, these genetic variants are the best recognised cause of primary deficiency of DPD associated with severe toxicity. Patients identified as having one or more copies of these variants should be considered for dose modification of fluoropyrimidines or alternative therapy. The test determines which variants are present and the full guidance allows for interpretation of the results and how the dosage of fluoropyrimidine should be adjusted, or in some cases omitted entirely and alternative agents sought.
The full guidance is available here: https://www.theacp.org.uk/userfiles/file/resources/dpd-testing-ukcb-july-2020-final.pdf