Thymic tumors

Thymic epithelial tumors are rare malignancies, that may be aggressive and difficult to treat, with variable prognosis. The histopathological classification distinguishes two major tumor types: thymomas, which reproduce the architecture of the normal thymus, combining thymic epithelial tumor cells, and non-tumoral lymphocytes, and thymic carcinomas. Autoimmune manifestations are observed in nearly one third of patients at diagnosis; myasthenia gravis is the most common, followed by pure red cell aplasia and hypogammaglobulinemia. The most widely used staging system is the Masaoka system, reviewed by Koga; a TNM system is currently under development. Assessing the resectability of the tumor represents the first stage of the therapeutic strategy, as complete resection is the most significant prognostic factor on patient survival. If complete resection seems possible upfront, surgery is the first step of the treatment, and is possibly followed by postoperative radiotherapy. For unresectable thymic tumors, pre-treatment biopsy is performed, and treatment is then based on induction chemotherapy followed by surgical resection or radiotherapy. Patients with no eligibility to focal treatment receive chemotherapy alone. Following a call of the French National Cancer Institute, a network of expert centers for the management of thymic malignancies started in in 2012: RYTHMIC.