Predictors of recurrence after thymoma resection.

Purpose: Recurrence rate is considered a better measure of clinical outcomes after thymoma resection than overall survival due to the indolent behavior of thymomas. This study was designed to determine predictors of recurrence after thymoma resection.
Materials and Methods: A single-institution, retrospective study was performed, including 305 patients who had undergone thymoma resection between 1986 and 2009.
Results: Among 305 patients, recurrence was observed in 41 patients (13.4%). The recurrence rates were 0% (0/19), 6.3% (4/63), 4.2% (2/48), 18.6% (11/59) and 20.7% (24/116) for type A, AB, B1, B2 and B3 tumors, respectively. The recurrence rate according to Masaoka stage was 6.1% (8/132), 11.4% (13/114), 26.8% (11/41) and 50.0% (9/18) for stages I, II, III and IV, respectively. After univariate analysis, completeness of resection (R0 versus R1), World Health Organization (WHO) histologic type (A, AB, B1 versus B2, B3), Masaoka stage, and size of tumor (<8 cm versus ≥8 cm) demonstrated significant differences with freedom from recurrence. Upon multivariate analysis, Masaoka stage was the only independent predictor of recurrence.
Conclusion: WHO histologic type, Masaoka stage, and size of tumor were associated with recurrence. Particularly, Masaoka stage was the only independent predictor of recurrence after thymoma resection.