BACKGROUND Non-small cell lung cancer (NSCLC) has a poor prognosis even for early stages of the disease (stage I and II). We studied the prognostic value of PET FDG in patients with completely resected stage I and II NSCLC. METHODS Retrospective study of 96 patients with NSCLC whose staging included 18F-FDG PET (fluoro deoxy glucose positron emission tomography). Histopathological stage was either stage I (75) or stage II (n=21). FDG uptake was measured as maximal standardized uptake value for body weight (SUVmax). Mean follow-up was 45+/-30 months (1-142 months). Overall and cancer-free survival rates were recorded. RESULTS SUVmax were higher for stage II than for stage I (10.5+/-4.5 vs 8.5+/-5, p=0.04). Mean tumor volumes were equivalent for both stages (33 cm3, p=0.18), excluding a partial volume effect. The median SUVmax in the whole study population was 7.8. The median survival was significantly longer in patients with a lower (SUVmax<or=7.8) FDG uptake (127 months vs 69 months, p=0.001). For stage I tumors (n=75), high FDG uptake was significantly associated with reduced median survival: 127 months if SUVmax<or=7.8 and 69 months if SUVmax>7.8 (p=0.001). For stage II tumors (n=21), no statistical difference was observed: 72 months vs 40 months for SUVmax<or=7.8 and for SUVmax>7.8, respectively (p=0.11), although there was a clear trend towards reduced survival for highly metabolic tumors. Disease-free survival was also significantly better for lower metabolic tumors: 96.1 months vs 87.7 months (p=0.01). CONCLUSIONS High FDG uptake is associated with reduced overall survival and disease-free survival of patients with completely resected stage I-II NSCLC. Whether patients with highly metabolic tumors should undergo a closer postoperative surveillance or adjuvant chemotherapy has to be addressed in a properly designed prospective trial.