Prognostic factors for thymic epithelial neoplasms, with emphasis on tumor staging

The prognosis of thymic epithelial tumors depends on their separation into thymoma and thymic carcinoma, as well as the extent to which they involve adjacent tissues and organs. To formalize evaluations of the latter attribute, several staging systems have been developed over the past 30 years. These include the Masaoka, Bergh, Wilkins-Castleman, Groupe d'Etudes des Tumeurs Thymiques, and tumor-nodal-metastasis schemes. The first of those formulations is most commonly employed in clinical practice, at least in the United States. The author believes that surgical-pathologic staging is the most powerful and reliable prognosticator for thymoma, as compared with histologic subtype-related prediction of behavior for that tumor type. Those topics, as well as affiliated issues concerning tissue sampling and staging techniques, are discussed in this article.