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5-FU (5Fluorouracil) is one of the most common chemotherapies on the market. It is often used to treat cancers of the breast, stomach, pancreas, colon, rectum, head and neck and is given through an IV or infusion. Approved in 1950, it has been the primary treatment for colorectal cancer for more than 60 years.

While common side effects include:

  • diarrhea
  • loss of appetite, nausea and/or vomiting
  • mouth sores
  • taste changes (such as metallic taste in mouth during infusion)
  • risk of infection
  • hair thinning or loss,

an important question to ask your doctor before starting a 5-FU regime is whether you have a DPD deficiency.


What is DPD Deficiency?

Dihydropyrimidine dehydrogenase (DPD) deficiency is a rare but serious disorder that affects 2-8% of the population.

DPD deficiency - when severe – is often diagnosed in infancy, however less severe cases can go unnoticed until an individual is given 5-FU or capecitabine (Xeloda). A DPD deficiency means you cannot breakdown the 5FU or capecitabine. These drugs can build up to a toxic level, and if untreated, can result in death.

SEE ALSOQuestions to Ask Your Doctor Before, During & After Treatment

How Can I Tell if I am DPD Deficient?

Signs of DPD deficiency include extreme or severe side effects when given the 5-FU or capeciabine, including:

  • mouth sores
  • diarrhea
  • vomiting
  • low white blood cell count
  • low platelet counts
[caption id="attachment_2431" align="alignright" width="194"]Dr. Laura Porter, MD, stage IV colon cancer survivor and Colon Cancer Alliance Patient Advocate & Medical Advisor. Dr. Laura Porter, MD, stage IV colon cancer survivor and Colon Cancer Alliance Patient Advocate & Medical Advisor.[/caption]

While it is common for these side effects occur to a moderate degree in most people receiving 5FU or capecitabine, if you find that you are having a severe reaction, further investigation should be done. We recommend talking to your doctor immediately. Many people with DPD deficiency can continue on chemotherapy at a reduced dose.

SEE MORE: Colorectal Cancer Treatment Side Effects

In December 2015, the Food and Drug Administration approved Vistogard (uridine triacetate) for the emergency treatment of adults and children who receive an overdose of the cancer treatment 5-FU or capecitabine, or who develop certain severe or life-threatening toxicities within four days of receiving these cancer treatments.

A special thank you to Dr. Laura Porter for compiling this information.

 Don’t forget, the Colon Cancer Alliance serves as a source of information about colon health. If you have additional questions about treatment or are in need of support, please contact our free Helpline at (877) 422-2030. We’re here to help! 


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