Your Genetic Blueprint Could Make Cancer Treatment Safer
Chemotherapy: one size does not fit all
Chemotherapy saves lives — but it can also cause severe side effects in certain patients. Often, the reason lies in our DNA: small inherited differences in genes that control how our bodies process drugs.
Pharmacogenetic testing can detect these differences before treatment begins, allowing oncologists to adjust the drug or dosage to reduce life-threatening toxicity and avoid ineffective therapy.
Three well-proven examples where genetics matter
1. Fluoropyrimidines (5-FU, capecitabine) — DPYD gene Variants in the DPYD gene can drastically reduce DPD enzyme activity, leading to severe or fatal toxicity. Around 4–5% of cancer patients in some European cohorts carry actionable variants. Testing is now recommended before prescribing these drugs.
2. Irinotecan — UGT1A1 gene The UGT1A1*28 variant increases the risk of severe neutropenia. Its frequency varies by ancestry, reaching over 40% in African ancestry populations. Knowing a patient’s status helps tailor dosing safely.
3. Thiopurines (mercaptopurine, azathioprine) — TPMT & NUDT15 genes Low enzyme activity in TPMT or NUDT15 can cause dangerous bone marrow suppression. Roughly 10% of people carry one low-activity allele, and 1 in 300 have very low/absent activity — directly informing safer starting doses.
Is testing cost-effective?
For DPYD testing, studies show modest added costs per patient but significant gains in quality-adjusted life years (QALYs). Broader pre-emptive pharmacogenomic panel testing has also been shown to be cost-effective in many healthcare models.
Why pre-emptive testing (the “genetic passport”) makes sense
Traditionally, testing happens reactively — only when a drug is prescribed or after a bad reaction. Pre-emptive testing stores your pharmacogenetic profile in your medical record, ready for any future prescription.
With falling costs of whole-genome sequencing (WGS), capturing all relevant pharmacogenetic variants in one go is now feasible. Several national pilots — even in newborns — are testing the concept.
Bottom line for patients
Certain chemotherapy drugs have genetic tests that can prevent severe harm — ask about DPYD, UGT1A1, TPMT, and NUDT15 before treatment.
Evidence shows testing is clinically useful and often cost-effective.
Pre-emptive and whole-genome strategies could make safer, personalised prescribing routine in the near future.
Your DNA might not just guide your treatment — it could save your life.