Impact of ¹⁸F-FDG PET/CT, CT and EBUS/TBNA on preoperative mediastinal nodal staging of NSCLC

Staging of non-small-cell lung cancer (NSCLC) is a multidisciplinary process involving imaging, endoscopic and surgical techniques. This study aims at investigating the diagnostic accuracy of ¹⁸F-FDG PET/CT, CT scan, and endobronchial ultrasound/transbronchial needle aspirate (EBUS/TBNA) in preoperative mediastinal lymph nodes (MLNs) staging of NSCLC.

We identified all patients who were diagnosed with NSCLC at the King Hussein Cancer Center in Amman, Jordan, between July 2011 and December 2017. We collected their relevant clinical, radiological, and histopathological findings. The per-patient analysis was performed on all patients (N = 101) and then on those with histopathological confirmation (N = 57), followed by a per-lymph-node-station basis overall, and then according to distinct N-stage categories.

¹⁸F-FDG PET/CT, in comparison to CT, had a better sensitivity (90.5% vs. 75%, p = 0.04) overall and in patients with histopathological confirmation (83.3% vs. 54.6%), and better specificity (60.5% vs. 43.6%, p = 0.01) overall and in patients with histopathological confirmation in MLN staging (60.6% vs. 38.2%). Negative predictive value of mediastinoscopy, EBUS/TBNA, and ¹⁸F-FDG PET/CT were (87.1%), (90.91%), and (83.33%) respectively. The overall accuracy was highest for mediastinoscopy (88.6%) and EBUS/TBNA (88.2%), followed by ¹⁸F-FDG PET/CT (70.2%). Dividing patients into N1 disease vs. those with N2/N3 disease yielded similar findings. Comparison between ¹⁸F-FDG PET/CT and EBUS/TBNA in patients with histopathological confirmation shows 28 correlated true positive and true negative findings with final N-staging. In four patients, ¹⁸F-FDG PET/CT detected metastatic MLNs that would have otherwise remained undiscovered by EBUS/TBNA alone. Lymph nodes with a maximal standardized uptake value (SUVmax) more than 3 were significantly more likely to be true-positive.

Multimodality staging of the MLNs in NSCLC is essential to provide accurate staging and the appropriate treatment. ¹⁸F-FDG PET/CT has better overall diagnostic utility when compared to the CT scan. The NPV of ¹⁸F-FDG PET/CT in MLNs is reliable and comparable to the NPV of EBUS/TBNA. SUVmax of MLNs can help in predicting metastases, but nevertheless, a positive ¹⁸F-FDG PET/CT MLNs particularly if such a result would change the treatment plan, should be verified histopathologically.