The IASLC/ITMIG thymic epithelial tumors staging project: Proposals for the T component for the forthcoming (8th) edition of the TNM classification of malignant tumors

Despite longstanding recognition of thymic epithelial neoplasms, there is no official American Joint Committee on Cancer/ Union for International Cancer Control stage classification. This article summarizes proposals for classification of the T component of stage classification for use in the 8th edition of the tumor, node, metastasis classification for malignant tumors. This represents the output of the International Association for the Study of Lung Cancer and the International Thymic Malignancies Interest Group Staging and Prognostics Factor Committee, which assembled and analyzed a worldwide database of 10,808 patients with thymic malignancies from 105 sites. The committee proposes division of the T component into four categories, representing levels of invasion. T1 includes tumors localized to the thymus and anterior mediastinal fat, regardless of capsular invasion, up to and including infiltration through the mediastinal pleura. Invasion of the pericardium is designated as T2. T3 includes tumors with direct involvement of a group of mediastinal structures either singly or in combination: lung, brachiocephalic vein, superior vena cava, chest wall, and phrenic nerve. Invasion of more central structures constitutes T4: aorta and arch vessels, intrapericardial pulmonary artery, myocardium, trachea, and esophagus. Size did not emerge as a useful descriptor for stage classification. This classification of T categories, combined with a classification of N and M categories, provides a basis for a robust tumor, node, metastasis classification system for the 8th edition of American Joint Committee on Cancer/Union for International Cancer Control stage classification

The IASLC/ITMIG thymic epithelial tumors staging project: Proposals for the N and M components for the forthcoming (8th) edition of the TNM classification of malignant tumors

Stage classification is an important underpinning of management of patients with cancer, and rests on a combination of three components: T for tumor extent, N for nodal involvement, and M for more distant metastases. This article details an initiative to develop proposals for the first official stage classification system for thymic malignancies for the 8th edition of the stage classification manuals. Specifically, the results of analysis of a large database and the considerations leading to the proposed N and M components are described. Nodal involvement is divided into an anterior (N1) and a deep (N2) category. Metastases can involve pleural or pericardial nodules (M1a) or intraparenchymal pulmonary nodules or metastases to distant sites (M1b)