Treatment Outcome of Thymic Epithelial Tumor: Prognostic Factors and Optimal Postoperative Radiation Therapy / 대한방사선종양학회지

ABSTRACT

PURPOSE: This study was conducted to analyze treatment outcome and prognostic significance of World Health Organization (WHO)-defined thymic epithelial tumor (TET) subtype and to assess optimal radiation target volume in patients receiving surgery and adjuvant radiation therapy with TET. MATERIALS AND METHODS: The record of 160 patients with TET, who received surgical resection at the Samsung medical Center, from December 1994 to June 2004, were reviewed. 99 patients were treated with postoperative radiation therapy (PORT). PORT was recommended when patients had more than one findings among suspicious incomplete resection or positive resection margin or Masaoka stage II~IV or WHO tumor type B2~C. PORT performed to primary tumor bed only with a mean dose of 54 Gy. The prognostic factor and pattern of failure were analyzed retrospectively. RESULTS: The overall survival rate at 5 years was 87.3%. Age (more than 60 years 77.8%, less than 60 years 91.1%; p=0.03), Masaoka stage (I 92.2%, II 95.4%, III 82.1%, IV 67.5%; p=0.001), WHO tumor type (A-B1 96.0%, B2-C 82.3%; p=0.001), Extent of resection (R0 resection 92.3%, R1 or 2 resection 72.6%; p=0.001) were the prognostic factors according to univariate analysis. But WHO tumor type was the only significant prognostic factor according to multivariate analysis. Recurrence was observed in 5 patients of 71 Masoka stage I-III patients who received grossly complete tumor removal (R0, R1 resection) and PORT to primary tumor bed. Mediastinal recurrence was observed in only one patients. There were no recurrence within irradiation field. CONCLUSION: WHO tumor type was the important prognostic factor to predict survival of patients with TET. This study suggest that PORT to only primary tumor bed was optimal. To avoid pleura- or pericardium-based recurrence, further study of effective chemotherapy should be investigated.