Relevance of positron emission tomography (PET) in oncology

Background: The clinical use of positron emission tomography (PET) for detection and staging of malignant tumors is rapidly increasing. Furthermore, encouraging results for monitoring the effects of radio- and chemotherapy have been reported. Methods: This review describes the technical principles of PET and the biological characteristics of tracers used in oncological research and patient studies. The results of clinical studies published in peer reviewed journals during the last 5 years are summarized and clinical indications for PET scans in various tumor types are discussed. Results and Conclusions: Numerous studies have documented the high diagnostic accuracy of PET studies using the glucose analogue F-18-fluordeoxyglucose (FDG-PET) for detection and staging of malignant tumors. In this field, FDG-PET has been particularly successful in lung cancer, colorectal cancer, malignant lymphoma and melanoma. Furthermore, FDG-PET has often proven to be superior to morphological imaging techniques for differentiation of tumor recurrence from scar tissue. Due to the high glucose utilization of normal gray matter radiolabeled amino-acids like C-ll-methionine are superior to FDG for detection and delineation of brain tumors by PET. In the future, more specific markers of tumor cell proliferation and gene expression may allow the application of PET not only for diagnostic imaging also but for non-invasive biological characterization of malignant tumors and early monitoring of therapeutic interventions.