Role of Radiation Therapy for Stage III Thymoma

Chun, Ha Chung; Lee, Myung Za

Abstract

PURPOSE: To evaluate the effectiveness and tolerance of the postoperative radiation therapy for patients with Stage III thymoma and to define the optimal radiotherapeutic regimen.
MATERIALS AND METHODS
We retrospectively analyzed the records of 24 patients with Stage III thymoma who were referred for postoperative radiation therapy in our institution from June, 1987 to May, 1999. Surgical therapy consisted of total resection in one patient, subtotal resection in seventeen, and biopsy alone in six patients. Age of the patients was ranged from 20 to 62 years with mean age of 47 years. Male to female ratio was 14 to 10. Radiation therapy was delivered with linear accelerator producing either 6 MeV or 10 MeV photons. The irradiated volume included anterior mediastinum and known residual disease. The supraclavicular fossae were not irradiated. The delivered total dose was ranged from 30 to 56 Gy. One patient received 30 Gy and eighteen patients received minimum of 50 Gy. Follow up period was ranged from 12 months to 8 years with median follow up of 40 months.
RESULTS
The overall local control rate for entire group of patients was 67% at 5 years. The cumulative local failure rates at one, three and five year were 18%, 28% and 33%, respectively. In patients treated with subtotal resection and biopsy alone, local control rate was 76% and 33%, respectively. The actuarial observed survival rate at 5 years was 57%, and actuarial adjusted survival at 5 years was 72%. The difference between 5 year survival rates for patients treated with subtotal resection and biopsy alone was not statistically significant (62% vs 30%).
CONCLUSION
We might conclude that postoperative radiation therapy was safe and effective treatment for patients with Stage III thymoma. Postoperative radiation therapy is recommended in cases where tumor margin is close or incomplete resection is accomplished.