Diagnostic accuracy and clinical impact of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in Positron Emission Tomography - Computed Tomography (PET-CT)-positive mediastinal lymphadenopathies in patients with thoracic or extra-thoracic malignancies.

Background: The high sensitivity of PET-CT can identify hypermetabolic mediastinal adenopathies during cancer management, but specificity is low and a biopsy is sometimes required to eliminate benign adenopathies.

Methods: This prospective diagnostic accuracy study included patients with hypermetabolic mediastinal lymphadenopathies revealed on PET-CT during either the initial management of a cancer, treatment evaluation, or monitoring. All patients underwent EUS-FNA. Diagnoses of malignancy based on cytological analysis following EUS-FNA were compared with clinical and radiological follow-up information. The treatment strategy decided before the results of the EUS-FNA pathology reports (Multidisciplinary Team Meeting [MTM-1]) was recorded and compared to the treatment strategy decided once pathological data from EUS-FNA were available (MTM-2).

Main Findings: Between 2013 and 2018, 75 patients were included with 47 eligible and evaluable patients. Sensitivity, specificity, and positive and negative predictive values of EUS-FNA were 93%, 100%, 100% and 90%, respectively. The concordance value between the therapeutic strategies determined for MTM-1 and MTM-2 was 44.7%. There were no significant differences in the intensity of fixation on PET-CT between malignant and benign lesions.

Conclusion: The diagnostic accuracy of the minimally invasive EUS-FNA procedure is sufficiently robust to avoid the need for diagnostic surgery. The combination of PET-CT and EUS-FNA may alter the therapeutic strategy that would be considered after PET-CT alone.

Registration: NCT01892501.