Abstract
BackgroundIntegrated 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is widely performed in hilar and mediastinal lymph node (HMLN) staging of non-small cell lung cancer (NSCLC). However, the diagnostic efficiency of PET/CT remains controversial. This retrospective study is to evaluate the accuracy of PET/CT and the characteristics of false negatives and false positives to improve specificity and sensitivity.Methods219 NSCLC patients with systematic lymph node dissection or sampling underwent preoperative PET/CT scan. Nodal uptake with a maximum standardized uptake value (SUVmax) >2.5 was interpreted as PET/CT positive. The results of PET/CT were compared with the histopathological findings. The receiver operating characteristic (ROC) curve was generated to determine the diagnostic efficiency of PET/CT. Univariate and multivariate analysis were conducted to detect risk factors of false negatives and false positives.ResultsThe sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/ CT in detecting HMLN metastases were 74.2% (49/66), 73.2% (112/153), 54.4% (49/90), 86.8% (112/129), and 73.5% (161/219). The ROC curve had an area under curve (AUC) of 0.791 (95% CI 0.723-0.860). The incidence of false negative HMLN metastases was 13.2% (17 of 129 patients). Factors that are significantly associated with false negatives are: concurrent lung disease or diabetes (p<0.001), non-adenocarcinoma (p<0.001), and SUVmax of primary tumor >4.0 (p=0.009). Postoperatively, 45.5% (41/90) patients were confirmed as false positive cases. The univariate analysis indicated age > 65 years old (p=0.009), well differentiation (p=0.002), and SUVmax of primary tumor ≦4.0 (p=0.007) as risk factors for false positive uptake.ConclusionThe SUVmax of HMLN is a predictor of malignancy. Lymph node staging using PET/CT is far from equal to pathological staging account of some risk factors. This study may provide some aids to pre-therapy evaluation and decision-making.
Highlights
Lung cancer is the leading cause of cancer death worldwide and late diagnosis at an advanced stage is a fundamental obstacle to improving lung cancer outcomes
Even though contrast enhanced CT has been the most common imaging modality for TNM staging, it has limitations in evaluating lymph node status because the prediction of positive lymph nodes on CT is based on size criteria alone [5]. 18Ffluorodeoxyglucose positron emission tomography (18F-FDG PET) is a functional imaging modality that is based on the increased glucose metabolism of malignant cells [6]
Some previous studies have indicated that the integrated PET/CT are more effective for detecting hilar and mediastinal lymph node (HMLN) metastasis, results regarding the extent of its benefits have been inconsistent [7]
Summary
Lung cancer is the leading cause of cancer death worldwide and late diagnosis at an advanced stage is a fundamental obstacle to improving lung cancer outcomes. The incidence of occult lymph node metastasis in NSCLC patients showing negative uptake by FDG-PET/CT is 7-16% [8,9,10], and false positive findings from inflammatory or granulomatous lesions are still problematic on PET/CT. Integrated 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is widely performed in hilar and mediastinal lymph node (HMLN) staging of non-small cell lung cancer (NSCLC). The diagnostic efficiency of PET/CT remains controversial This retrospective study is to evaluate the accuracy of PET/CT and the characteristics of false negatives and false positives to improve specificity and sensitivity. Results: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/ CT in detecting HMLN metastases were 74.2% (49/66), 73.2% (112/153), 54.4% (49/90), 86.8% (112/129), and 73.5% (161/219). This study may provide some aids to pre-therapy evaluation and decision-making
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