Molecular imaging with positron emission tomography (PET) using [18F] fluorodeoxyglucose (FDG) has been suggested as an early, sensitive marker of tumour response to anticancer drugs by monitoring the changes in glucose metabolism in tumours. Recently, FDG-PET has shown to be highly sensitive in detecting early response in other tumours. In this study, the investigators will prospectively investigate the role of early FDG-PET (at day 7 and week 6) in outcome prediction.