TY - JOUR T1 - Fluctuation in Plasma 5-Fluorouracil Concentration During Continuous 5-Fluorouracil Infusion for Colorectal Cancer JF - Anticancer Research JO - Anticancer Res SP - 6193 LP - 6199 VL - 35 IS - 11 AU - HIDEO MATSUMOTO AU - HIDEO OKUMURA AU - HARUAKI MURAKAMI AU - HISAKO KUBOTA AU - MASAHARU HIGASHIDA AU - ATSUSHI TSURUTA AU - KAORU TOHYAMA AU - TOSHIHIRO HIRAI Y1 - 2015/11/01 UR - http://ar.iiarjournals.org/content/35/11/6193.abstract N2 - Background/Aim: It is generally believed that the plasma concentration of 5-fluorouracil (5-FU) is constant when 5-FU is continually administered for chemotherapy. The aim of the present study was to verify whether this is true. Patients and Methods: Nine patients with colorectal cancer were enrolled in this study. All patients received chemotherapy; four patients received FOLFIRI (leucovorin, 5-fluorouracil, irinotecan) and five received FOLFOX (leucovorin, 5-fluorouracil, oxaliplatin). 5-FU was administered continuously (2400 mg/m2) for 46 h. Serum was collected at 12 points after the start of administration. The concentration of 5-FU was evaluated using a new immunoassay method and gas chromatography–mass spectrometric (GC/MS) method. Results: The concentrations of 5-FU fluctuated dramatically over time, with greater than 3-fold changes in each individual, and the pattern was not constant. Conclusion: Because the serum concentration of 5-FU fluctuates and displays various patterns, the dosage should not be based on body surface area. A new individualized method for determining the 5-FU dosage should be developed. ER -