A thymine-challenge test to prospectively evaluate dihydropyrimidine dehydrogenase activity for risk of severe 5-fluorouracil-induced gastrointestinal toxicity.

ABSTRACT:

Purpose

Inherited dihydropyrimidine dehydrogenase (DPD) deficiency is a risk factor for severe 5-fluorouracil toxicity. We report a phenotyping approach (thymine challenge test) to prospectively determine DPD activity and the association with severe adverse events.

Methods

The primary aim of this prospective study was to determine whether a thymine challenge test could prospectively identify patients at risk of severe toxicity from treatment with 5-fluorouracil/capecitabine in combination chemotherapy schedules or monotherapy. The focus was prediction of those at risk of ≥ grade 3 gastrointestinal toxicity. DPD activity was determined from the thymine/dihydrothymine (THY/DHT) ratio measured in a urine sample after a thymine test dose (250 mg, oral).

Results

Of the 166

SUBMITTER: Helsby N 

PROVIDER: S-EPMC12361283 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature