18F-5-fluorouracil dynamic positron emission tomography/computed tomography shows decreased tracer activity after bevacizumab in colorectal metastases.

Objective: The aim of this study was to evaluate the potential of fluorine-18 (F)-5-fluorouracil (F-5-FU) positron emission tomography/computed tomography (PET/CT) to show differences in 5-FU activity in metastatic colorectal cancer before and after treatment with bevacizumab.

Methods: This was a pilot study of five patients with newly diagnosed and untreated metastatic colorectal adenocarcinoma. The presence of cancer was confirmed by histopathological analysis before enrollment.