P2.04-009 Tumor Size Did Not Affect Masaoka Staging as Predictors of Recurrence in Thymoma: Topic: Thymic Malignancies Clinical and Translational

Abstract

This single-institution retrospective study assessed the predictive value of Masaoka stage plus tumor size in predicting thymoma recurrence following resection. Four models using binary logistic regression were developed for evaluating the relationship of tumor size and Masaoka stage in predicting recurrence. Model I and II included Masaoka stage and median tumor size, respectively. Model III included these two values and their interaction terms (Masaoka stage × medium tumor size). Model IV did not include the interaction between the two parameters as it was not significant. Model IV was determined to be the best model as it had the lowest -2LogL and used the least number of included parameters. Using Model IV, Masaoka stage positively correlated with recurrence of thymoma (P = 0.001). The risk of recurrence of the patients with Masaoka stage III-IV was significantly higher than that of patients with Masaoka stage I (OR= 36.17, 95% CI: 4.30-304.48, P = 0.001). However, inclusion of tumor size did not influence the predictive value of Masaoka staging for tumor recurrence (P = 0.137). The data suggest that Masaoka stage plus tumor size is not a better alternative to Masaoka stage alone for tumor recurrence following tumor resection in patients with thymoma.