Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Capecitabine is a chemotherapy medicine taken as tablets. The body converts it, step by step and largely inside tumour tissue, into fluorouracil (5-FU), which stops cancer cells from making the DNA they need to divide. It is used for bowel cancer, breast cancer and some cancers of the stomach and pancreas. It is sold as Xeloda, among other names.
DPYD makes the enzyme dihydropyrimidine dehydrogenase, which breaks down most of the fluorouracil that capecitabine turns into. A few DPYD variants (among them *2A, rs3918290, and c.2846A>T, rs67376798) make less working enzyme; people who carry one have far more of the drug active for longer, with a much higher chance of severe side effects. About 3 to 8 in 100 people of European ancestry carry one such variant. CPIC and DPWG have published guidelines on DPYD, and the US drug label discusses it. Other genes such as TYMS, CDA and MTHFR have been studied, with weaker evidence.
Clinical guidelines that name a gene for Capecitabine. They sort people into groups by the gene copies they carry.
CPIC guideline: DPYD. DPYD activity score 0 to 2. Strong. 2018.
DPWG guideline: DPYD. DPYD activity score 0 to 2. 2020.
US FDA: DPYD. DPYD activity score 0 to 1.5. 2025.
Every published finding on gene variants and Capecitabine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
DPYD rs67376798: Level 1A · replicated. Toxicity: Neoplasms. 28.
DPYD rs3918290: Level 1A · replicated. Toxicity: Neoplasms. 28.
DPYD rs2297595: Level 1A · replicated. Toxicity: Neoplasms. 17.
DPYD rs1801158: Level 1A · replicated. Toxicity: Neoplasms. 13.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Studies of side effects in people carrying a variant.
DPYD rs3918290: Genotype CT is associated with decreased dose of capecitabine.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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