Implementing DPYD testing prior to treatment with fluoropyrimidines at Lahey Clinic.
45 Background: Fluoropyrimidines are foundational therapies for the treatment of many cancers. Carriers of pathogenic DPYD variants face a 5–8 fold increased risk of grade ≥3 toxicity. In 2025, the FDA added a boxed warning to the capecitabine label recommending DPYD testing prior to treatment initiation. Despi...