National clinical guidelines don't mention screening cancer patients for DPYD gene variants, but hospital pharmacy leaders are forging ahead with the patient safety practice, the American Society of Health-System Pharmacists reported March 6.
DPYD tests work to identify patients with dihydropyrimidine dehydrogenase deficiency, which can cause them to experience serious adverse reactions to capecitabine or 5-fluorouracil, also known as 5-FU.
Patients with this metabolism deficiency have a risk of serious toxicity higher than 70%, Daniel Hertz, PharmD, PhD, a pharmacy professor at the University of Michigan College of Pharmacy, told the ASHP. 5-FU treatments can be fatal for these patients.
Wentworth-Douglass Hospital in Dover, N.H., reduces starting 5-FU doses by 25% to 50% in an effort to ensure tolerability and safety. Experts said minimizing starting doses of the popular chemotherapy have not affected cancer treatment efficacy.
"If we're treating 1,000 of these patients every year, we're bound to find 50-70 patients that could be at risk for very severe toxicity, hospitalizations, and even potentially drug-related fatality by receiving standard dosing," Jai Patel, PharmD, an associate research director at Charlotte, N.C.-based Levine Cancer Institute, told the ASHP.
Screening patients for DPYD gene variants is the norm in Europe, according to the ASHP, but the American Society of Clinical Oncology and the U.S. National Comprehensive Cancer Network don't include this practice in their guidelines.