Adjuvant radiation therapy for stage II thymoma

Background. Thymoma is difficult to study because of its indolent natural history. The criteria for administration of adjuvant radiation therapy remain controversial, and it is unclear whether patients with Masaoka stage H thymoma benefit from adjuvant radiation. The goal of this report was to determine whether or not this group benefits from radiation therapy in terms of disease-specific survival and tumor recurrence. Methods. Case records of the Massachusetts General Hospital were retrospectively reviewed from 1972 to 1999. One hundred fifty-five patients underwent resection for thymoma, of which, 49 had stage II disease. The world literature was reviewed using a Medline search (1966 to 2001), and a secondary review of referenced works was performed. Results. Fourteen stage II patients underwent radiation therapy. Thirty-five did not receive radiation therapy., Baseline prognostic factors between radiated and nonradiated groups were similar. All patients underwent complete resection. The addition of adjuvant radiotherapy did not significantly alter local or distant recurrence rates in stage H thymoma. Disease-specific survival at 10 years in stage II patients was 100% with radiotherapy and without radiotherapy (p = 0.87). There was one recurrence in the nonradiated group at 180 months, which was outside the usual radiation portal. Conclusions. Most stage II patients do not require adjuvant radiation therapy and can be observed after complete resection.