The Value of Transesophageal Echography in the Clinical Staging of Lung Cancer

Abstract

The noninvasive preoperative assessment of lung cancer is currently based on CT scan. This technique is used to find out the local extension of the tumor and to identify the presence of mediastinal adenopathies by distinguishing as accurate as possible between benign and metastatic adenopathies according to their size. When CT scan suggests the presence of suspected mediastinal lymph nodes, invasive diagnostic methods are indicated to confirm whether the lymph nodes are affected (transbronchial needle aspiration, mediastinoscopy, mediastinotomy and thoracoscopy).

Transesophageal echography (TEE) was first used in the 80’s as a diagnostic guide in the clinical classification of gastrointestinal tumors and may be of help in the mediastinal evaluation of lung cancer as well. Several studies have demonstrated the value of TEE in detecting mediastinal adenopathies and mediastinal structures involvement (great vessels and mediastinal organs) by assessing the direct growth of the primary tumor which is crucial in the surgical decision.

To distinguish benign from metastatic nodes TEE, unlike CT scan, does not consider their size only but other issues as shape, definition of edges and echografic structure. Generally speaking, TEE detects more adenopathies than CT scan but not in all mediastinal stations since it is limited by the presence of air; thus, adenopathies located in the upper mediastinum, mainly on the right side, are usually missed by TEE. The areas more clearly visualized are the subcarinal, paraesophageal, tracheobronchial and hilar ones and mainly those located in the aortopulmonary window. Currently, TEE can be used also to guide a thin needle toward the lymph nodes and to perform its aspiration biopsy. In conclusion, transesophageal and/or endobronchial echography are developing promising diagnostic methods which provide additional information that can influence the clinical decision making process and the prognosis. They are well tolerated by the patients but time is needed to find out their role. Lastly, their usefulness will depend also on their feasibility since an expensive equipment and specifically well trained staff are needed.