Prescribing patterns of chemotherapy drugs to Australian cancer patients

Abstract

Introduction: The three cancer chemotherapy drugs 5-fluorouracil (antimetabolite drug), doxorubicin (anthracycline drug), and paclitaxel (taxane drug) represent well established agents within their drug classes. Despite their age, little is known about how these drugs are used in the clinic. The primary objective of this project was to examine the prescribing rates of the three drugs, with a secondary objective to examine their rates of dose reductions. Methods: A retrospective analysis was conducted of oncology medical and pharmacy dispensing records from a single location (Concord Repatriation General Hospital) located in Sydney, Australia. Data related to patient characteristics, cancer diagnosis, chemotherapy protocol, drug dose and dose reductions were included in this study if the patient had received their last round of chemotherapy between January and December 2015. Results: From the project cohort, 52% of patients were treated with at least one of the three study drugs. The drugs were not used in isolation but were combined with between one and six other chemotherapy drugs for their treatment. The majority of patients were prescribed at least one of the study drugs with 63% of patients treated with 5-flurouracil given a dose reduction; for doxorubicin and paclitaxel these numbers were 41 and 42%, respectively. Some (56%) of patients were also given dose reductions in their non-study chemotherapy drugs. The magnitude of the dose reductions was between 5 and 30%. Four patients received two dose reductions during their treatment, while two patients were prescribed three dose reductions. The reasons for the dose reductions were not routinely noted in the medical records. Conclusions: Despite their age, 5-flurouracil, doxorubicin, and paclitaxel are still commonly used in the clinic to treat a variety of human cancers and are being used alongside newer drugs. Because of their side effects, more than half of the patients treated with one of the three drugs were prescribed a dose reduction. Future research stemming from the project could include a larger cohort of patients taken from multiple hospital sites, evaluating the reasons behind the dose reductions, examining the correlation between dose reduction and patient outcomes, and patient co-morbidities/co-prescribing and dose reductions and patient outcomes.