Darling et al report findings from the Early Lung PET trial for non-small cell lung cancer. PET-CT had 70% sensitivity and 94% specificity for identifying cancerous mediastinal lymph nodes (with invasive staging as the reference standard). Sounds good. However, among the 22 patients with PET-CT scans positive for mediastinal nodes, 8 did not have cancer in their nodes on invasive staging. Don't use a PET that's positive for mediastinal nodes to exclude patients from curative surgery; invasive mediastinal staging is required on all patients, authors argue.