Prediction of true-negative lymph node metastasis in clinical IA non-small cell lung cancer by measuring standardized uptake values on positron emission tomography.

PURPOSE: We developed a method for predicting true-negative lymph node metastases in clinical IA non-small lung cancer (NSCLC) by the combined evaluation of computed tomography (CT), 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) findings and the maximum standardized uptake value (SUVmax) of primary tumors.

METHODS: The subjects of this study were 94 patients with clinical stage IA NSCLC who underwent both preoperative CT and FDG-PET. We analyzed the relationship between the SUVmax of primary tumors and various clinicopathological factors to find the best method available for assessing true-negative lymph node metastasis.

RESULTS: The pathological stages were IA (n = 80), IB (n = 4), IIA (n = 5), IIIA (n = 4), and IV (n = 1). Pathologic lymph node metastasis was recognized in nine patients and the SUVmax of these tumors ranged from 3.3 to 20.3. A SUVmax of 3.0 was defined as the cut-off point and patients were dichotomized according to this point. Tumors with SUVmax of 3.0 or less were associated with a significantly lower incidence of pleural and vascular invasion and were characterized by the degree of differentiation.

CONCLUSION: The SUVmax of primary tumors reflects the grade of malignancy; therefore, the combined evaluation of FDG-PET/CT findings with the SUVmax of primary tumors may help predict lymph node metastasis negativity.