IPM Take
This is a small technical update with a large political message. If genomic safety tests are built mainly around the populations in which they were first designed, precision medicine can reproduce inequality while appearing scientifically advanced. The NHS update matters because it shows that equity is not an abstract value in pharmacogenomics. It is a design requirement inside the test panel itself.
Executive Summary
Manchester University NHS Foundation Trust reported that routine DPYD genetic testing used to guide fluoropyrimidine chemotherapy has been strengthened by including an additional variant linked to African ancestry, DPYD c.557A>G. Until last year, UK testing looked for four main DPYD variants typically found in White European populations. Since implementation at the North West Genomic Laboratory Hub in September 2025, three patients of African ancestry at risk of toxicity have started chemotherapy at adjusted doses. Further implementation is underway at the other six Genomic Laboratory Hubs in England.
Why it matters
- Diagnostics / pathology: Need to ensure genomic panels reflect population diversity, not only historically dominant evidence bases.
- Clinicians: Should understand that a “negative” pharmacogenomic result may depend on which variants were included in the test.
- Patients / advocates: Can use this as a concrete example of why diverse genomic evidence is essential for safer cancer care.
Previously, some patients could receive a false sense of safety from pharmacogenomic testing if their relevant genetic variants were not included in the panel. In fluoropyrimidine chemotherapy, DPYD testing is used to reduce the risk of severe and sometimes fatal toxicity from medicines used across cancers including colorectal, breast and gastric cancer.
What changed is that the NHS is beginning to correct an ancestry blind spot in routine cancer pharmacogenomics. The North West Genomic Laboratory Hub introduced testing for the fifth DPYD variant, c.557A>G p.Tyr186Cys, from 22 September 2025, alongside direct testing for DPYD c.1129-5923C>G. The laboratory notification states that c.557A>G is a decreased-function variant found in about 2% of individuals of African ancestry and recommends inclusion in routine testing.
The eligible population is not a single cancer group. Fluoropyrimidines are widely used across cancer treatment, and NHS Race and Health Observatory states that up to 40% of the 38,000 patients treated with fluoropyrimidine-based chemotherapy in England each year are at risk of an adverse drug reaction.
The implementation lesson is direct: inclusive genomic medicine requires inclusive variant selection. Otherwise, the pathway may be precise for one population and incomplete for another.
