Paraneoplastic Syndromes and Thymic Malignancies: An Examination of the International Thymic Malignancy Interest Group Retrospective Database

Abstract

Introduction Thymic epithelial tumors (TETs) are associated with paraneoplastic autoimmune (PN/AI) syndromes. Myasthenia gravis is the most common PN/AI syndrome associated with TETs. Methods The International Thymic Malignancy Interest Group (ITMIG) retrospective database was examined to determine (i) baseline and treatment characteristics associated with PN/AI syndromes and (ii) the prognostic role of PN/AI syndromes for patients with TETs. The competing risks model was used to estimate cumulative incidence of recurrence (CIR) and the Kaplan-Meier method was used to calculate overall survival (OS). A Cox proportional hazards model was used for multivariate analysis. Results 6670 patients with known PN/AI syndrome status were identified from 1951-2012. PN/AI syndromes were associated with younger age, female sex, type B1 thymoma, earlier stage, and an increased rate of total thymectomy and complete resection status. There was a statistically significant lower CIR in the PN/AI (+) group compared to the PN/AI (-) group (10-year 17.3% vs. 21.2%, respectively, p=0.0003). The OS was improved in the PN/AI (+) group compared to the PN/AI (-) group (HR 0.63, 95% CI 0.54-0.74, P<0.0001, median OS 21.6 years versus 17.0 years, respectively). However, in the multivariate model for recurrence-free survival and OS, PN/AI syndrome was not an independent prognostic factor. Discussion Previously, there has been mixed data regarding the prognostic role of PN/AI syndromes for patients with TETs. Here, using the largest dataset in the world for TETs, PN/AI syndromes were associated with favorable features (i.e. earlier stage, complete resection status) but were not an independent prognostic factor for TETs.