Staging of non-small cell lung cancer (NSCLC) has undergone a significant evolution, from plain chest radiographs to anatomical imaging, invasive techniques and, most recently, metabolic imaging using positron emission tomography (PET) scans. Even the literature regarding PET imaging has undergone significant evolution. Initial reports were characterised by compelling yet anecdotal images. This was followed by approximately 10 years of studies showing that mediastinal staging by PET was superior to computed tomography (CT) which, of course, was not surprising because CT had already been shown to be notoriously misleading in many situations. Eventually authors began addressing the clinically more relevant question of whether PET can replace invasive mediastinal staging. The article by Tournoy and colleagues¹ in this issue of Thorax illustrates how far we have come (see page 696). Not only does this study use the most sophisticated technology—an integrated PET/CT scanner—but, more importantly, the authors have elevated the science a notch by thoughtfully evaluating nuances of scan interpretation in order to maximise what can be gained from this staging modality.

The overall scientific quality of the study by Tournoy and colleagues is good. An appropriate gold standard was used by requiring a surgical staging procedure after a negative needle staging test (transoesophageal ultrasound with needle aspiration, transbronchial needle aspiration, etc, which carry a 20–30% false negative rate).² The authors should also be commended for looking at enlarged and normal size nodes separately, since PET uptake in smaller nodules …