Positron Emission Tomography Measurement of Fluorouracil Uptake Prior to Therapy and Chemotherapy Response

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 liver metastases was 23% [1]. The metabolism of FU has been studied and was recently summarized by Hull et al. [2]. These authors found no significant difference in the metabolite concentrations in plasma between responders and nonresponders to FU chemotherapy. They state that the detection of FU metabolites in tumor tissue is required for an assessment of response to FU. Shani and Wolf showed in an animal study that drug-responsive tumors had a 20: 1 tumor-to-blood ratio 12 h after injection, while drug-resistant tumors had only a 4:1 ratio [3]. These data indicate that FU metabolite measurements in tumor tissue may be helpful in predicting response to FU chemotherapy in patients.