Dihydropyrimidine dehydrogenase (DPD)

Our bodies have a gene that produces the dihydropyrimidine dehydrogenase enzyme, which helps break down certain medications in the liver.

If there is mutation in the gene, your body will not produce enough of the dihydropyrimidine dehydrogenase enzyme. This condition is called dihydropyrimidine dehydrogenase deficiency (DPD).

Having DPD can cause fluorouracil-based chemotherapy drugs (which are commonly used in colon cancer treatment) to build up in your body and cause severely toxic reactions.

Note: It has been shown that pretreatment genetic testing for DPD may reveal a need to reduce fluoropyrimidine-based treatments (fluorouracil [FU], capecitabine, and other analogs) to avoid potential lethal toxicities.

Because DPD mutations occur in less than 3% of the population, testing is usually not required unless a patient has an adverse reaction during treatment with fluorouracil-based chemotherapy drugs. The FDA advises physicians to inform patients of the potential for serious and life-threatening adverse reactions due to DPD deficiency. They should also discuss with patients whether they should be tested to determine their risk when using fluoropyrimidine-based chemotherapy.

If you are experiencing side effects such as uncontrollable nausea, vomiting, or diarrhea, very low blood counts, high fevers, or extreme weakness during treatment with fluorouracil-based chemotherapy drugs, contact your doctor immediately.