Changing pattern of secondary cancers among patients with malignant thymoma in the USA.

<bold>Background: </bold>The risk of developing secondary cancers (SCs) among patients with malignant thymoma in the US has not been estimated in the more recent time period. Methods: We extracted demographic and treatment data from the SEER database to estimate the standardized incidence ratios (SIRs). Results: Of 1570 patients with thymoma 211 (13.4%) had SCs. The overall risk of developing SCs was higher among patients with thymoma (SIR: 1.54, 95% CI: 1.34-1.76). The SIRs for cancers of lung, esophagus, sigmoid colon, soft tissue and heart, kidney, NHL and leukemia was significantly higher as compared to the general US population. Conclusions: Patients with thymoma are at modestly elevated risk of developing SCs as compared to the general US population. Although the overall risk has not changed after 14 additional years of follow up, the distribution of SCs has significantly broadened, with increased diversity across type and anatomic location of SCs. [ABSTRACT FROM AUTHOR]