5-fluorouracil (5-FU) has been the most widely used agent in the treatment of early stage and advanced colorectal cancer. Traditionally, 5-FU dosing is based on body surface area (BSA). However, BSA-dosing has been associated with a wide range of pharmacokinetic (PK) variability, resulting in marked differences in drug exposure and toxicities in an individual. There is a significant association between the risk of 5-FU-related toxicities and the extent of 5- FU systemic exposure, which can be measured using a well-established pharmacokinetic (PK) assay.
