The clinical application of positron emission tomography to colorectal cancer management.

Colorectal cancer (CRC) is the second commonest cancer in the Western World. Successful treatment relies significantly on accurate detection and staging of primary disease as well as the early identification of the presence and extent of recurrence. Morphological imaging techniques, particularly computed tomography (CT), are well established and widely available to carry out these tasks in addition to predicting and monitoring response to therapy. This review analyses the current inadequacies for imaging CRC and critically assesses the potential role of functional imaging with positron emission tomography (PET). We review the current literature, use our experience from the first 1000 PET studies carried out at our Institution and the perspective of surgical colleagues. We find little evidence for the use of 2-[18F]fluoro-2-deoxy-D-glucose (FDG)-PET for screening asymptomatic individuals and current modalities appear better suited for detection of symptomatic primary CRC. There is evidence of increased accuracy for FDG-PET in staging primary disease, but this area remains controversial and larger studies are necessary. The situation is quite the reverse with respect to imaging suspected recurrent disease with FDG-PET being more sensitive and specific than conventional techniques. This benefit manifests itself through alteration in patient management and results in cost savings. PET also appears to have a specific place in the evaluation of patients undergoing radiotherapy and chemotherapy, a role that will expand. The evidence suggests that PET will ultimately become routinely incorporated into CRC patient management algorithms. Technological advances coupled with novel tracer research will facilitate this.