Introduction -
5-Fluorouracil (5-FU) is commonly used in gastrointestinal and breast cancer regimens. Although the route of administration (oral and IV) does not affect the efficacy, each route does present a different set of toxicity profile. DPD (dihydropyrimidine dehydrogenase) deficiency, although rare, can lead to lethal side effects. Testing for this is not readily available and funded by the PBS, however patients can self fund through some pathology providers.
Methods -
We did a retrospective audit of all new chemotherapy regimens containing 5-FU commenced in 2022 at Latrobe Regional Hospital This was then cross referenced with calls to SURC (symptoms and urgent review clinic) and hospital admission in order to grade toxicities. Comparison was made between oral and IV administration to see if one route had more toxicities.
Results
In 2022 there were 100 patients started on 5-FU based regimen, 63 IV based and 37 oral based. There were a higher number of calls to SURC for chemotherapy related toxicities in the oral (67%) compared to the IV (39%). The most common toxicity was diarrhea, accounting for 64% in IV compared to 50% in oral.
In terms of grade 3 toxicity leading to hospital admission, it was 7.9% in the IV compared to 13.5% in the oral group.
Further data collection and analysis is in progress.
Discussion
Oral 5FU which is more convenient to administer, leads to more calls to SURC for chemotherapy related toxicities and higher percentage of hospital admissions. IV 5FU takes up more resources in the chemotherapy day unit but appears to be more tolerable. DPD testing on all new patients may lead to reduced number of admissions and chemo toxicities. The cost of DPD deficiency testing for all patients receiving 5-FU in 1yrs would be around $16800.