Volumetric analysis of the thymic epithelial tumors: correlation of tumor volume with the WHO classification and Masaoka staging

Thymic epithelial tumors (TETs), known as thymoma and thymic carcinoma, are the most common primary neoplasms of the anterior mediastinum. They have a broad spectrum of biological and morphological features. The World Health Organization (WHO) classification (1) based on the morphology of the epithelial cells and ratio of the lymphocytes to epithelial cells is the most widely used classification of thymomas and thymic carcinomas. In the 2015 WHO classification, TETs were classified into two major categories; six subtypes of thymomas (type A, atypical type A variant, AB, B1, B2, and B3) and thymic carcinomas (2,3). It has been reported that the WHO histological classification reflects both the clinical and the functional features of TET and is useful for preoperative diagnosis and selection of treatment strategy in patients with TET (3-5). There are no randomized clinical trials that provide definitive guidance for the management of TETs. However, National Comprehensive Cancer Network (NCCN) (6) and International Thymic Malignancy Interesting Group (ITMIG) (7) indicates treatment options for TETs. Their consensus is that non-invasive TETs (stage I) can be treated with surgery alone, with no adjuvant therapy. Invasive TETs and residual TETs are recommended radiation and/or chemotherapy given as adjuvant therapy. Locally advanced TETs (stage III), solitary metastasis or ipsilateral metastasis (stages IVa) are indicated neoadjuvant therapy. TETs with evidence of extrathoracic metastases are recommended chemotherapy