Radiotherapy in thymic tumors

Abstract

Thymic tumors, defined as neoplasms of thymic epithelial cells, are the most common anterior mediastinal tumors in adults (approximately 20 % of anterior mediastinal tumors) with heterogeneous biological, oncological, and histological characteristics. The incidence is frequent between the fourth and sixth decades (Lewis et al. Cancer 60(11):2727–2743, 1987). No risk factors are evident aside from strong correlation with myasthenia gravis and other paraneoplastic syndromes (Safieddine et al. J Thorac Oncol: Off Publ Int Assoc Study Lung Cancer 9(7):1018–1022, 2014). Aside from diagnosis by chance in a chest X-ray or computerized tomography (CT) scan or diagnosis based on paraneoplastic syndromes like myasthenia gravis (MG, approximately 45 % of thymomas) and thymoma that was found in 10–15 % of MG cases (Muller-Hermelink et al. Ann NY Acad Sci 681:56–65, 1993; Detterbeck and Parsons Annals Thorac Surg 77(5):1860–1869, 2004), local pressure symptoms such as chest pain, dyspnea, coughing, and venous congestion could lead to the diagnosis of thymoma or thymic carcinoma. Invasive thymomas and thymic carcinomas consist of only 0.2–1.5 % among all thymic tumors, and radiotherapy could play an important role in their treatment due to their radiosensitivity; however, their low incidence and slow natural growth increase the difficulty to delineate the role of radiotherapy aside from the retrospective series in the literature.