Biomarker-Guided Fluorouracil in Treating Patients With Colorectal Cancer Receiving Combination Chemotherapy

OBJECTIVES: Primary * To determine whether 4 courses of pharmacokinetic (PK)-guided 5-fluorouracil chemotherapy improves the ability to achieve a targeted area under the curve (20 to 25 mg\*hr/L) in patients with colorectal cancer receiving mFOLFOX6 chemotherapy as compared to historical non-PK-guided therapy in patients treated with a similar FOLFOX regimen. Secondary * To determine and compare the incidence of neutropenia and diarrhea in patients treated with these regimens. OUTLINE: This is a multicenter study. * Standard mFOLFOX6 (course 1): Patients receive fluorouracil IV bolus over 1-5 minutes followed by fluorouracil IV continuously over 46 hours, oxaliplatin IV over 2 hours, and leucovorin calcium IV over 2 hours on day 1. Patients undergo plasma sample collection periodically during study for pharmacokinetic (PK)-guided fluorouracil dose determination for courses 2-4. * PK-guided mFOLFOX6 (courses 2-4): Patients receive fluorouracil bolus, oxaliplatin, and leucovorin calcium as in course 1. Patients also receive fluorouracil\* IV continuously as determined by the PK-guided analysis. NOTE: \*The continuous infusion fluorouracil dose adjustment is calculated based on the results of PK plasma concentrations and the corresponding AUC from the preceding course.