A pioneering update to routine genetic testing developed by the North West Genomic Laboratory Hub (GLH) is helping improve cancer treatment safety for patients of African ancestry, addressing a long‑standing gap in care that has contributed to health inequalities.
The updated test strengthens screening for patients receiving fluoropyrimidine chemotherapy by incorporating an additional gene variant linked to African ancestry – a change that could help prevent serious and potentially fatal side effects in some patients.
Until recently, routine genetic testing in England assessed only four main DPYD variants, which are most commonly found in people of White European ancestry.
In 2024, a systematic review published by the NHS Race and Health Observatory, in partnership with the University of Liverpool, highlighted how this approach failed to capture important genetic differences in ethnic minority populations. The review identified a clear need to improve testing to reduce inequalities in cancer treatment outcomes.
Following these findings, it was recommended that a fifth DPYD variant, more commonly associated with African ancestry, be added to routine testing across England.
The enhanced test went live in September 2025 at Manchester University NHS Foundation Trust’s North West GLH.
Since its introduction, three patients of African ancestry identified as being at high risk of adverse reactions have already responded positively to adjusted chemotherapy plans informed by the test. Implementation of the fifth variant testing is now underway across the other six Genomic Laboratory Hubs in England.
The update represents one of the first examples of research‑driven genomic reform being rapidly translated into routine NHS clinical practice.
DPYD testing examines variations in the dihydropyrimidine dehydrogenase (DPD) enzyme, which is responsible for breaking down fluoropyrimidine chemotherapy drugs used to treat many cancers.
People with DPD deficiency may be unable to metabolise these drugs effectively, putting them at risk of severe toxicity, including damage to the bone marrow, bowel and skin. In rare cases, reactions can be fatal.
By identifying patients with relevant genetic variants in advance, clinicians can adjust chemotherapy doses or choose alternative treatment approaches, significantly improving safety.
The improved test is delivered from the Liverpool site of the North West GLH, which provides DPYD testing for more than 450 patients each month across the North West of England.
The hub was among the first NHS genomic laboratories to introduce routine clinical testing for the fifth DPYD variant, helping lead national efforts to improve equity in precision medicine.
The findings are particularly significant because adverse reactions in patients of non‑European ancestry are less likely to have been recorded or attributed to genetic factors under previous testing regimes.
Chief Executive of the NHS Race and Health Observatory, Professor Habib Naqvi, said:
“Our work has led to a groundbreaking outcome in the use of chemotherapy, which is already having a positive impact on patient’s lives. Genomics and precision medicine are currently at the cutting edge of medical technology, promising a world in which treatments can be more targeted and effective. However, we also know that ethnic minority groups are under-represented in medical research and in genomic biobanks. Research needs to be conducted with diverse populations – only then can medical advances benefit everyone.”
Historically, DPYD variants more prevalent in diverse ethnic groups were not routinely screened across the NHS, limiting clinicians’ ability to personalise treatment and contributing to poorer outcomes for some patients.
Including the fifth variant, c.557A>G,means that three patients in the North West, aged 47, 59 and 76, are now starting chemotherapy at adjusted doses, reducing their risk of severe drug reactions while ensuring they can still access effective cancer treatment.
By embedding inclusive genetic testing into routine NHS pathways, the approach supports safer treatment decisions and helps address inequalities that have persisted across cancer outcomes.
Work is now ongoing to ensure consistent rollout of the enhanced DPYD testing approach nationwide, with the potential to improve survival and quality of life for many more patients.
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