Abstract
BackgroundStaging of mediastinal lymph nodes in non-small cell lung cancer (NSCLC) is mandatory. The maximum Standard Uptake Value (SUVmax) obtained using F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is the best non-invasive technique available for this evaluation, but its performance varies from center to center. The aim of the present study was to identify FDG-PET predictors of mediastinal malignancy that are able to minimize intercenter variability and improve the selection of subsequent staging procedures.MethodA multicenter study of NSCLC patients staged through FDG-PET and endobronchial ultrasonography with needle aspiration (EBUS-NA) was performed using therapeutic surgery with systematic nodal dissection as gold standard. Intercenter variability and predictive power for mediastinal malignancy of different FDG-PET measures were assessed, as well as the role of these measures for selecting additional staging procedures.ResultsOne hundred and twenty-one NSCLC patients, of whom 94 (72%) had ≥1 hypermetabolic spots in the mediastinum, were included in the study. Mean SUVmax of the primary tumor was 12.3 (SD 6.3), and median SUVmax of the highest hypermetabolic spots in the mediastinum was 3.9 (IQR 2.4-7). Variability of FDG-PET measures between hospitals was statistically significant (p = 0.016 and p < 0.001 respectively), but lost significance when SUVmax in the mediastinum was expressed as a ratio or a subtraction from the primary tumor (SUVmax mediastinum/tumor, p = 0.083; and SUVmax mediastinum - tumor, p = 0.428 respectively). SUVmax mediastinum/tumor showed higher accuracy in the ROC analysis (AUC 0.77 CI 0.68-0.85, p < 0.001), and showed predictive power for mediastinal malignancy when using a 0.4 cutoff (OR 6.62, 95%CI 2.98-14.69). Sensitivities and negative predictive values of clinical staging through EBUS-NA attained values ranging between 57% and 92% after FDG-PET, which improved with additional techniques when the tumor had a diameter >3 cm and/or a SUVmax mediastinum/tumor ratio >0.4.ConclusionThe SUVmax mediastinum/tumor ratio is a good predictor of regional tumor extension in NSCLC. This measure is not influenced by intercenter variability and has an accuracy of over 70% for the identification of malignancy when using a 0.4 cutoff.
Highlights
Staging of mediastinal lymph nodes in non-small cell lung cancer (NSCLC) is mandatory
Variability of fluorodeoxyglucose positron emission tomography (FDG-PET) measures between hospitals was statistically significant (p = 0.016 and p < 0.001 respectively), but lost significance when maximum Standard Uptake Value (SUVmax) in the mediastinum was expressed as a ratio or a subtraction from the primary tumor (SUVmax mediastinum/tumor, p = 0.083; and SUVmax mediastinum - tumor, p = 0.428 respectively)
SUVmax mediastinum/ tumor showed higher accuracy in the Receiver Operating Characteristic (ROC) analysis (AUC 0.77 confidence intervals (CI) 0.68-0.85, p < 0.001), and showed predictive power for mediastinal malignancy when using a 0.4 cutoff
Summary
Staging of mediastinal lymph nodes in non-small cell lung cancer (NSCLC) is mandatory. The maximum Standard Uptake Value (SUVmax) obtained using F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is the best non-invasive technique available for this evaluation, but its performance varies from center to center. The maximum Standard Uptake Value (SUVmax) provides information on the metabolic activity of the primary tumor and its regional lymph nodes. It is usually increased in the mediastinum when lymph nodes show malignant infiltration, high FDG uptake may be observed in inflammatory diseases. The use of ratios between SUVmax values in the mediastinum and the tumor has been proposed as a way of homogenizing the results obtained at different centers and allows the definition of cutoffs that may not be influenced by intercenter variability [13,14,15]
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