NEW ORLEANS—The goal of nursing care for dihydropyrimidine dehydrogenase (DPD) enzyme deficient patients is to promote and practice prevention by anticipating and managing risks for toxicity, according to research presented at the Oncology Nursing Society 37th Annual Congress.

The fluoropyrimidines 5-fluorouracil (5-FU) and its prodrug capecitabine are standard chemotherapeutic agents used for treating various solid tumors in adults, including digestive tract, breast, and head and neck cancers. Fifty years after discovery, 5-FU is the most prescribed antineoplastic drug worldwide with approximately 2 million patients treated each year.

DPD is a rate-limiting enzyme responsible for metabolizing approximately 80% of 5-FU. Patients who are partially or totally deficient in DPD activity cannot adequately degrade fluoropyrimidines. It is estimated that 3% to 5% of patients receiving 5-FU have this deficiency. These patients can develop severe multiorgan system toxicities such as pancytopenia, mucositis, nausea, vomiting, diarrhea, volume depletion, neurological changes, and in some cases fatality. In addition, more than 5 mutations in the DPD gene have been identified in people with the DPD deficiency.

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Screening tests for DPD deficiency are available, but genetic testing of patients prior to initiating therapy is controversial and not widely practiced. Therefore, nurses must be astute and use sound judgment to recognize the condition, anticipate patient needs, and adapt necessary care accordingly.

Gina DiMeo, RN, OCN, and colleagues at Memorial Sloan-Kettering Cancer Center, New York, NY, aimed to identify areas in which nurses should receive further education and explain the significant role they needed to play in order to manage and prevent complications of DPD deficiency.

The group identified that nursing care as well as patient education are needed in the areas of oral hygiene, aggressive hydration, electrolyte management, nutrition, analgesia administration, neurologic status, supportive medications, colony stimulating factors and transfusions, and reducing the risk of infection and

sepsis. Patient awareness about the issue and its potential complications should also be a priority before initiating therapy. Once therapy has begun, nursing practice should shift toward providing education, monitoring, and follow-up.

Nurses should be aware that adverse effects of DPD deficiency may postpone or interrupt 5-FU treatment, thereby decreasing the cure rate, the researchers stated. The issue is often not addressed because it is very rare, but it deserves attention because afflicted patients experience extremely severe, worsening symptoms, hospital treatment is usually expensive, and the condition is very difficult to manage, said Carla Vassallo, RN, BSN, one of the study authors.

“Early reporting of signs and symptoms of adverse effects is critical to both symptom management and patient safety,” the nursing group concluded.