Accuracy and predictive features of FDG-PET/CT and CT for diagnosis of lymph node metastasis of T1 non-small-cell lung cancer manifesting as a subsolid nodule.

OBJECTIVES: To retrospectively evaluate the diagnostic accuracy and predictive features of F-18 fluorodeoxyglucose positron emission tomography/ computed tomography (FDG-PET/CT) and CT in lymph node (LN) staging of T1 non-small-cell lung cancers (NSCLCs) manifesting as subsolid nodules.
METHODS: From January 2005 to May 2011, 160 patients with pathologically proven T1 subsolid NSCLCs with LN staging were included in this study. Diagnostic accuracies of FDG-PET/CT and CT for LN staging were evaluated. Maximum standardised uptake value (SUVmax) and CT features of primary tumours were evaluated to investigate predictive factors for LN metastasis.
RESULTS: LN metastases were found in nine of the 160 patients (5.6%). No LN metastasis was present in patients with a solid proportion ≤50%. Sensitivity, specificity and accuracy of FDG-PET/CT for LN staging on a per-patient basis were 11.1%, 86.1% and 81.9%; those of CT were 11.1%, 96.7% and 91.9%. Among patients with a solid proportion >50%, there were significant differences in SUVmax, solid portion size, solid proportion and lesion location between patients with and without LN metastasis. Multivariate analysis revealed that higher SUVmax, a larger solid proportion and central location were independent predictors of LN metastasis.
CONCLUSIONS: FDG-PET/CT adds little value to CT in the lymph node staging of T1 subsolid NSCLCs. KEY POINTS: Lymph node (LN) metastases are important in non-small-cell lung cancer (NSCLC). • Positron emission tomography (PET) helps to stage solid NSCLCs. • FDG-PET/CT adds little to the LN staging of T1 subsolid NSCLCs. • No LN metastasis in patients with a solid proportion ≤50%. • LN metastasis is more common in solid and/or centrally sited tumours.