The Challenge of Mediastinal Staging

Abstract

Lung cancer staging is a crucial step in both correct prognosis and therapy. Mediastinal staging in particular is usually accomplished using imaging techniques such as computed tomography and 18F–glucose positron-emission tomography, minimally invasive techniques, i.e. transbronchial needle aspiration with or without ultrasound guidance (endobronchial ultrasound) and transoesophageal ultrasound-guided fine needle aspiration and surgical procedures, i.e. mediastinoscopy, thoracoscopy. Each of these techniques has its own sensitivities, specificities and predictive values that must be thoroughly considered within the staging route, with the aim of achieving the best result with the least resource consumption and the least discomfort to the patient; the correct evaluation of a negative result on the basis of its predictive value is essential as well. In this article we suggest a mathematical model that can predict the probability of nodal metastasis after a certain number of diagnostic procedures has been performed, providing an objective way of evaluating whether a patient is fit for surgery or, conversely, whether further investigations are required.

Competence in endosonographic techniques

“…However, the decision to avoid a surgical confirmation after a negative cytology from endobronchial or endoesophageal needle aspiration should take into consideration the residual probability of mediastinal metastasis after a negative cytology, and suggest direct resort to surgery only when the final probability is below a predefinite threshold; a mathematical model based upon Bayes' theorem was proposed by some authors to get an estimation of the residual probability of mediastinal involvement after every staging procedure. 34 There is evidence coming from prospective studies performed in experienced endosonography centers, that EBUS keeps a high sensitivity and concurrently mediastinoscopy may not improve diagnostic yield after a wellperformed negative endosonography with needle aspiration of at least three mediastinal nodal stations in patients with low (<35%) prevalence of mediastinal disease. 2,35,36 However, in a discordant manner, data from one prospective study published in 2010, 37 3 recent studies [38][39][40] among which two retrospective and one prospective, and a metaanalisis 41 report a low sensitivity in mediastinal staging (respectively 68% and 35-49%) in cN0-1 patients with negative mediastinum after Tc and PeT, hence, precisely in case of low prevalence of mediastinal metastasis.…”