Two large series have reported outcomes. In the first study, data was obtained from 1,320 Japanese patients. The Masaoka clinical stage was found to correlate well with prognosis of thymoma and thymic carcinoma. Patients with stage III thymoma underwent surgery and additional radiation therapy. Patients with stage IV thymoma were treated with radiation therapy or chemotherapy. For patients with stage III or stage IV thymoma, the 5-year survival rates were 93% for patients treated with total resection, 64% for patients treated with subtotal resection, and 36% for patients whose disease was inoperable. Prophylactic mediastinal radiation therapy did not appear to prevent local recurrences effectively in patients with totally resected stage III thymoma. Adjuvant therapy including radiation or chemotherapy did not appear to improve the prognosis in patients with totally resected stage III or stage IV thymoma.
In the second study, 1,334 patients diagnosed and treated between 1973 and 2005 were identified in a SEER database. At a relatively short median follow-up of 65 months, radiation therapy did not appear to increase the risk of cardiac mortality or secondary malignancy. Routine use of PORT did not appear to improve long-term survival.
Most invasive thymomas have been found to be relatively sensitive to cisplatin-based combination chemotherapy regimens. The combinations that follow have reported objective response rates from 79% to 100% with subsequent resectability rates ranging between 36% and 69%:[13,14,15,16,17,18,19,21]
Long-term survival rates following induction chemotherapy and surgery with or without radiation therapy and consolidation chemotherapy have ranged from 50% at 4 years, 77% at 7 years and, respectively, 86% and 76% for stage III and IV patients at 10 years in different published series.[14,16,17,22]
However, similar results have been reported with preoperative radiation therapy without chemotherapy, particularly if great vessels are involved (5-year overall survival rate of 77% and 10-year OS rate of 59%).[23,24]
An intergroup trial conducted in the United States reported a predicted 5-year OS rate of 52% in 26 patients receiving the PAC chemotherapy regimen followed by radiation therapy without surgery.
The role of surgical debulking for patients with either stage III or stage IVA disease is controversial. Phase II data suggests that prolonged survival can be accomplished with chemotherapy and radiation therapy alone in many patients presenting with locally advanced or even metastatic thymoma. Therefore, the value of surgery may be questioned if complete, or at the very least, near complete extirpation cannot be accomplished.
Current Clinical Trials
Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with stage III thymoma and stage IV thymoma. The list of clinical trials can be further narrowed by location, drug, intervention, and other criteria.