[en] Positron emission tomography (PET) has been widely used for several years for staging and response evaluation in oncology. It is time to critically review its role in routine patient care. [18F]-labelled fluorodeoxyglucose ([18F]-FDG) remains the radiotracer of choice in most indications. Its high sensitivity, the half-life of 110 minutes and the easy production of this radiotracer explain its routine use although the specificity is not very good. Infectious or inflammatory processes can mimic tumours. Appropriate selection of patients studied in the recommended indications and interpretation of images by an experienced team having access to both clinical information and other diagnostic studies allows reducing the risk of false positives. Although PET is highly accurate, not all patients suffering from cancer need a PET study. Major improvements were also observed with conventional imaging techniques over the past 10 years. It is important to avoid long waiting lists because otherwise treatment delay may counterbalance the benefit of PET studies.