Validation of finger prick testing for 5-fluorouracil drug level monitoring in cancer patients.

We intend to measure the 5-fluorouracil (5FU) blood plasma levels in finger prick samples from 50 patients receiving 5FU and compare them to a peripheral blood sample (the gold standard) with the aim of validating the finger prick test so that it can replace the peripheral blood test and enable better access and participation in the therapeutic drug monitoring of 5FU. Both the peripheral blood test and the finger prick test must occur on Day 2 of the 5FU infusion (when 5FU is at steady state) and both tests are in addition to standard of care treatment, so that only patients enrolled in this study will have a finger prick test. Every participant will return to the hospital (an extra visit when they would otherwise be at home) for these extra tests. After reading the finger prick test instructions, the finger prick test can be completed by the participant if they choose (very similar to blood sugar testing in diabetes), or be the performed by the clinical trial coordinator, trained at least 2 weeks prior to the first enrolment. Patient evaluation of the finger prick instructions & success of self-administration are a secondary endpoint of the study. The Clinical Trial Coordinator will perform the peripheral blood test. The results of these tests will not be used to change clinical management. Any 5FU dose changes are at the discretion of the treating medical oncologist. Once the participant has completed the Day 2 peripheral blood and finger prick test, they have completed the study, however continue in the study and repeat the testing for the next cycle of treatment if they choose.