Clinical Observation of Applying Intrabeam® Intraoperative Radiotherapy for the Treatment of Invasive Thymoma

Abstract

Purpose: Intraoperative radiotherapy (IORT) has been used to treat various solid tumors, and demonstrated advantages. However, no IORT has been reported to treat invasive thymoma. The current study tried to determine the safety profile of applying INTRABEAM IORT to the treatment of invasive thymoma. Materials and methods: Among the patients admitted to our hospital from September to December, 2016 who was diagnosed with invasive thymoma, 14 were selected as subjects. They were inquired for medical history and divided into 8 stage IIA cases and 6 stage IIB cases according to Masaoka staging system. Of the 14 patients, 5 had myasthenia gravis (MG). INTRABEAM radiation (8–10 Gy, low energy) was delivered to the postoperative tumor bed of each patient during operation. The intra- and post-operative complications were detected and evaluated, and the improvement of symptoms assessed. Results: One month after operation, only one patient presented cough and increased hemogram levels, chest CT (computerized tomography) showed pulmonary inflammation. Postoperative chest CT at 3 and 12 months showed that all the patients returned to normal, without cough or pulmonary fibrosis surrounding the radiation field. In addition, ultrasonic cardiography and electrocardiogram (ECG) demonstrated no significant difference before and after surgery. At the end of the follow-up, all the patients were alive, no relapse or remote metastasis had been found. Conclusion: It is safe to administer INTRABEAM IORT at a dose of about 10 Gy with low energy to patients with stage II invasive thymoma. The INTRABEAM IORT does not significantly increase operation- or radiation-related complications, has no significant effect on the vital organs around the radiation field, such as lung and heart. The long-term efficacy is worth expecting.