A new real‑world study from Nottingham University Hospitals has found that around 7% of cancer patients carry DPYD gene variants that can make standard chemotherapy drugs significantly more toxic. These drugs 0 including 5‑fluorouracil (5‑FU) and capecitabine - are widely used to treat cancers such as colorectal, breast, and pancreatic cancer.
What is the DPYD gene?
The DPYD gene affects how the body breaks down these treatments. When certain variants are present, patients can experience severe or even life‑threatening side effects unless their chemotherapy dose is adjusted.
The team analysed 1,478 patients treated with fluoropyrimidine‑based chemotherapy between 2021 and 2023. They looked at:
- How common DPYD variants were
- Whether prevalence differed by cancer type or ethnicity
- Whether socioeconomic deprivation affected access to testing
Key findings
The team found that 7% of all patients carried a DPYD variant. The highest rates were seen in colorectal cancer patients (7.9%), and the most common variant was HapB3, found in three‑quarters of all variant‑positive cases.
Variant rates differed slightly by ethnicity, but numbers were small for some groups. Crucially, socioeconomic status did not influence access to DPYD testing. Patients from the most deprived areas of Nottingham were just as likely to be tested as those from more affluent areas.
Why this matters
DPYD testing is now required across the NHS before starting fluoropyrimidine chemotherapy. Identifying patients with these variants allows clinicians to adjust doses and reduce the risk of serious toxicity.
This study provides reassuring evidence that the rollout of mandatory testing is reaching patients fairly, regardless of where they live or their socioeconomic background.
Research recommendations
The authors highlight the need for:
- Continued awareness of DPYD testing among clinicians and patients
- More comprehensive genetic testing methods to capture rare variants
- Ongoing monitoring to ensure equitable access across the UK
They also note that while the study shows equal access in Nottingham, patterns may differ in other regions.
