Evaluation of Modulated Fluorouracil Chemotherapy with Positron Emission Tomography in Patients with Metastatic Colorectal Cancer

Abstract

The standard chemotherapeutic agent for the treatment of hepatic metastases from colorectal cancer is 5-fluorouracil (FU) [1]. Depending on both the selection process and the response criteria used, the reported response rates have varied from 8% to 82% [1]. Based on a literature survey, Kemeny reported that the average response rate for hepatic metastases was 23%. The metabolism of FU has been studied extensively and was recently summarized by Hull et al. [2]. Therefore, modified treatment protocols including d, l-folinic acid have found use for therapy. Trave et al. demonstrated an increased inhibition of thymidilate synthase following pretreatment with d, l-folinic acid [3]. We examined patients with [¹⁸F]FU and positron emission tomography (PET) to obtain quantitative data about the distribution pattern of FU and metabolites in metastases, normal liver parenchyma, and aorta as a function of time. Our primary goal was to evaluate the effect of d, l-folinic acid pretreatment on the FU metabolite concentrations.