The Role of Postoperative Radiotherapy in the Management of Patients with Thymic Tumors - A Retrospective Study

Background: Thymomas are the most common tumor arising in the anterior mediastinum. Surgery is the cornerstone for the management of these tumors. The role of postoperative radiotherapy in Masaoka stage II thymomas remains controversial, but it is well established in the advanced stages. The aim of this study was to investigate the role of postoperative radiotherapy in the overall management of thymomas, and the evaluation of potential prognostic factors. Patients and Methods: Between 1989 and 2007, 41 thymoma patients underwent surgery and 27 of them received radiotherapy with a curative intent. The Masaoka staging system was used. The histopathological records and specimens of patients were thoroughly reviewed. Clinical and radiological evaluations took place every 6 months. The mean patient follow-up was 69 months (range: 2-212). Results: DFS (disease free survival), TS (total survival) and DSS (disease specific survival) differed significantly between stages and histological types (p<0.04). Stage I patients were managed only surgically, with none recurring or dying. Concerning stage II patients, TS was significantly longer in non-irradiated cases (10/21) (p=0.025). Stage III (n=8) and IV (n=8) patients underwent postoperative radiotherapy, with 4/8 of stage IV disease also receiving induction chemotherapy. Six out of 8 stage III-IV patients recurred (1 distant and 5 intrathoracic failure), out of whom 4 died due to disease progression despite further treatment (all type C histology). The mean DFS and TS for stage III patients were 49.2 and 50.3 months respectively, with the corresponding values for stage IV being 14.5 and 29.1 months. Patients with myasthenia had a favorable outcome and the ones with complete resection a significantly longer DFS (p=0.0003) and DSS (p=0.039). The Cox regression analysis showed that myasthenia and tumor size are important prognostic factors for DFS (p<0.05). Conclusion: Myasthenic patients have a more favorable prognosis. Radiotherapy can be omitted in totally resected stage I-II patients, whereas it is beneficial in more advanced stages. Thymomas typically occur in adults over 40 years and are the most common tumor arising in the anterior mediastinum (1). The symptomatology of patients with thymic malignancies varies widely and only one third of patients with localized disease are symptomatic. The majority of patients present with cough, dyspnea, upper respiratory complaints and chest discomfort or pain (2, 3). About 30% to 50% of patients with thymoma have myasthenia gravis (MG), whereas about 15% of patients with MG are diagnosed with thymomas (4). The most commonly used staging system is the one