Abstract
Background4′-[methyl-11C]-thiothymidine (4DST) is a novel positron emission tomography (PET) tracer to assess proliferation of malignancy. The diagnostic abilities of 4DST and 2-deoxy-2-18 F-fluoro-d-glucose (FDG) for detecting regional lymph node (LN) metastases of non-small cell lung cancer (NSCLC) were prospectively compared. In addition, the relationship between the PET result and the patient's prognosis was evaluated.MethodsA total of 31 patients with NSCLC underwent 4DST PET/computed tomography (CT) and FDG PET/CT. The PET/CT images were evaluated qualitatively and quantitatively for focal uptake of each PET tracer, according to the staging system of the American Joint Committee on Cancer. Surgical and histological results provided the reference standards. Patients were followed for up to two years to assess disease-free survival.ResultsOn a per-lesion basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for LN staging were 82%, 72%, 32%, 96%, and 73%, respectively, for 4DST, and 29%, 86%, 25%, 88%, and 78%, respectively, for FDG. The sensitivity of 4DST was significantly higher than that of FDG (P < 0.001). The disease-free survival rate with positive 4DST uptake in nodal lesions was 0.35, which was considerably lower than the rate of 0.83 with negative findings (P = 0.04). Among the factors tested, nodal staging by 4DST was the most influential prognostic factor (P = 0.05) in predicting the presence of a previously existing spread lesion or of a recurrence over the course of 2 years.Conclusion4DST PET/CT is sensitive for detecting mediastinal lymph node metastasis in NSCLC, but its low specificity is a limitation. However, it may be helpful in predicting the prognosis of NSCLC.
Highlights
Lymph node (LN) involvement and distant metastasis of non-small cell lung cancer (NSCLC) are indicators of a poor prognosis [1]
FDG positron emission tomography (PET)/computed tomography (CT) has been highly specific in mediastinal nodal staging, but it has been sensitive in a different range [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]
Even though integrated PET/CT helps improving the accuracy of mediastinal nodal staging, it is still insufficient for detection of microscopic lymph node metastases [22]
Summary
Lymph node (LN) involvement and distant metastasis of non-small cell lung cancer (NSCLC) are indicators of a poor prognosis [1]. Mediastinoscopy [4] and endobronchial ultrasonographytransbronchial needle aspiration (EBUS-TBNA) [5] show high sensitivity and specificity for LN staging, but they are invasive tests, and their ability to obtain a sample is dependent on the location of the lesion. Noninvasive imaging, such as CT and magnetic resonance imaging (MRI), has been used for NSCLC staging. 2-Deoxy-2-18F-fluoro-D-glucose (FDG) positron emission tomography (PET) has contributed to more accurate mediastinal staging of lung cancer with median sensitivity and specificity of 61% and 79%, respectively [6]. Even though integrated PET/CT helps improving the accuracy of mediastinal nodal staging, it is still insufficient for detection of microscopic lymph node metastases [22]
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