Comparison of patterns of relapse in thymic carcinoma and thymoma

Abstract

7539 Background: Thymic carcinomas (TC) are considered to be more aggressive than thymomas and carry a worse prognosis. Given their rarity, our knowledge about their clinical behavior and optimal management is limited. We reviewed our recent experience with the surgical management of thymic tumors and compared the outcomes and patterns of relapse between TC and thymoma. Methods: Retrospective review of a single institution surgical database. Data included patient demographics, stage, treatment, pathologic findings, and postoperative outcomes. Results: During the period 1995–2006, 120 patients with thymic tumors underwent surgery, including 24 patients with TC and 96 patients with thymoma by the WHO 2004 histologic classification. At a median follow-up of 41 months (range 6–154), the overall 5 year survival was significantly different between TC and thymoma (TC 57%, thymoma 89%, p=0.01). Data on relapse was available for 112 patients. The progression-free 5 year survival was also significantly different between TC and thymoma (TC 36%, thymoma 75%, p<0.01). Complete macroscopic resection (R0 and R1) resulted in significantly higher progression-free survival in both TC and thymoma. Relapses in TC occurred earlier and more frequently at distant sites than in thymoma. Sites of distant relapse included lung (4), bone (3), brain (1), liver (1) and skin (1), with some patients having multiple sites. Details are listed in the table below. Conclusions: Patterns of relapse differ between TC and thymoma with lower progression-free survival, earlier onset and more distant relapses in TC. Complete macroscopic resection affords significantly longer freedom from disease progression in both TC and thymoma. Despite significantly higher rates of distant relapse, good overall survival in TC can be achieved. Comparison of Patterns of Relapse in Thymoma and Thymic Carcinoma Thymic Carcinoma (n=22) Thymoma (n=90) 5 yr Progression-free Survival by Resection Status 5 yr Progression-free Survival by Resection Status Complete Resection (n=14) 59% p=0.01* Complete Resection (n=81) 87% p<0.01* Incomplete Resection (n=8) 0% Incomplete Resection (n=9) 0% Site of Progression (n=10) Site of Progression (n=14) Locoregional (n=4) 40% Locoregional (n=13) 93% p<0.01** Distant (n=6) 60% Distant (n=1) 7% Time to Progression (mo) Time to Progression (mo) Mean 14.0 Mean 31.1 p=0.05*** Median (Range) 9 (6–33) Median (Range) 21(4–95) * Log-Rank Test, Complete vs. Incomplete; ** Fisher’s Exact Test, TC vs. Thymoma; *** T-test, TC vs. thymoma. No significant financial relationships to disclose.