Economic evaluation of personalized vs. standard dosing of 5-fluorouracil in first-line chemotherapy for metastatic colorectal cancer in Australia

Aims: Using pharmacokinetics (PK)-guided 5-fluorouracil (5-FU) for metastatic colorectal cancer (mCRC) improves overall survival (OS) and decreases toxicity, yet its value for money in the Australian setting is unknown. Our study assesses the cost-effectiveness of PK vs. body surface area (BSA) dosing of 5-FU for patients with mCRC. Methods: We developed a semi-Markov model with four health states to compare PK-guided dosing within a FOLFOX regimen vs. BSA-guided dosing for mCRC patients from an Australian healthcare system perspective. Transition probabilities were derived from fitted survival models, with utility values obtained directly from published studies. We calculated direct healthcare costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs), and included both one-way and probabilistic sensitivity analyses. Results: BSA-guided FOLFOX provided 1.291 QALYs at a cost of $36 379, compared with PK-guided FOLFOX which delivered 1.751 QALYs at a cost of $32 564. Therefore, PK-guided dosing emerges as the dominant strategy offering both better health outcomes and lower costs. The variables that had the greatest impact on the overall ICER were the adverse event rates in the BSA and PK groups, model time horizon, utility of progression-free survival and PREDICT assay cost. Our univariate and multivariate sensitivity analysis confirmed that the ICER for PK FOLFOX consistently remained below $50 000 per QALY across all tested variables. Conclusions: PK dose management of 5-FU-based chemotherapy in mCRC patients appears to be a cost-saving strategy in Australia. However, our model estimates are drawn from limited, low-quality evidence. Further evidence from randomized controlled trials (RCTs), directly comparing PK-based to BSA-based dosing across a variety of current regimens, is needed to address our model's uncertainties.