Radiotherapy in thymic neoplasms

The role of adjuvant radiotherapy in thymic tumors has not been explicitly defined. Since epithelial thymic tumors are relatively radiosensitive, many clinicians advocate the use of adjuvant radiation therapy in all cases, in addition to those cases where there is extension beyond the capsule [1]-[4]. Justification for adjuvant radiation is based on studies showing decreased recurrence rates for stage II disease with adjuvant therapy from 30% to 5% [5, 6]. Other groups suggest that, due to the low incidence of local recurrence after complete resection of stage II thymomas, radiation therapy should be reserved for selected patients [7]-[10]. Schmidt-Wolf [11] proposed that adjuvant external-beam radiotherapy should be considered only for stages II and III disease where there were extensive adhesions between tumor and pleura, microscopic pleural infiltration, or macroscopic invasion of the pericardium, large vessels, or lung. In addition, Chen [12] noted that completely resected stage II thymomas of WHO subtype A, AB, and B-I may not require adjuvant therapy.