PET for response assessment in oncology: radiotherapy and chemotherapy

Positron emission tomography (PET) imaging with the glucose analogue fluorodeoxyglucose (FDG) is increasingly used to monitor tumour response in patients undergoing chemotherapy and chemoradiotherapy. Numerous studies have shown that FDG-PET is an accurate test to differentiate between residual viable tumour tissue and therapy-induced fibrosis. Furthermore, quantitative assessment of therapy-induced changes in tumour FDG uptake may allow prediction of tumour response and patient outcome very early in the course of therapy. Treatment may be adjusted according to the chemosensitivity and radiosensitivity of the tumour tissue in an individual patient. Thus, FDG-PET has enormous potential to reduce the side effects and costs of ineffective therapy. This review gives an overview of clinical studies on treatment monitoring with FDG-PET and discusses how the results of PET imaging may be used to change patient management.