ES 07.01 Endoscopic Staging of Lung Cancer

Abstract

Endoscopic Staging of Lung Cancer Kazuhiro Yasufuku During the management of patients with lung cancer, accurate lymph node staging is important not only to determine the prognosis but also to decide the most suitable treatment plan. Non-invasive staging such as computed tomography (CT) and positron emission tomography (PET) indicate size and metabolic activity, respectively. However imaging alone is inaccurate and therefore tissue sampling is the preferred and most reliable. Surgical staging by mediastinoscopy has been the gold standard for mediastinal lymph node staging but requires general anesthesia and complications cannot be ignored. Endoscopic ultrasound techniques provide a minimally invasive alternative for surgical staging and have become available for oncologists around the world. The current available endoscopic ultrasound techniques for mediastinal staging include transesophageal endoscopic ultrasound guided fine needle aspiration (EUS-FNA) and endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA). Both procedures are performed in an outpatient setting under local anesthesia. EUS-FNA is a sensitive and safe method of evaluating the inferior mediastinal nodes (stations 7, 8, and 9) and some parts of the anterior mediastinal nodes if the lymph nodes are accessible from the esophagus. However, in spite of the strength of EUS-FNA for evaluating the inferior mediastinal nodes, its ability to evaluate lesions anterior to the trachea is limited. On the other hand, EBUS-TBNA has reach to the paratracheal and subcarinal (stations 2R, 2L, 4R, 4L, 7), as well as the N1 lymph nodes (stations 10, 11, 12). In experienced hands, EBUS can be used through the esophagus for a EUS-like approach to sample inferior mediastinal lymph nodes. With the transvascular approach, AP window lymph nodes (station 5) can be sampled by EUS-FNA and/or EBUS-TBNA. Specialized centers have reported the sampling of station 6 via EUS-FNA. Thus, EUS-FNA and EBUS-TBNA are complementary methods for lymph node staging in lung cancer and most of the mediastinum and the hilum can be evaluated with these endoscopic procedures beyond the reach of mediastinoscopy. Based on the current evidence, EBUS-TBNA and EUS-FNA presents a minimally invasive endoscopic procedure of choice for mediastinal staging of NSCLC with discrete N2 or N3 lymph node enlargement, provided negative results are confirmed by surgical staging. When combined the techniques offer safe and accurate assessment of mediastinum, with accuracy surpassing that of the pervious gold standard – cervical mediastinoscopy. EBUS-TBNA and/or EUS-FNA can also be repeated with ease and have been used for mediastinal restaging in patients who underwent neoadjuvant therapy in preparation for definitive surgical intervention. New size needles are now available for sampling of the lymph nodes during EBUS-TBNA including 25-gauge and 19-gauge needles. Smaller needles may provide greater reach with good quality samples, whereas larger 19-gauge needle may provide bigger tissue for histological evaluation of the lymph nodes samples. There are limitations of using cytological samples obtained during EBUS-TBNA or EUS-FNA for PD-L1 expression. The use of the 19-gauge needle may solve this problem. EBUS, EUS, Invasive mediastinal staging