Impact of Prior Cancer History on Outcomes in Thymoma
Abstract Background Thymoma is an uncommon intrathoracic malignant tumor and has a long natural history. It is uncertain whether the survival of thymoma patient is affected by prior cancer history. Finding out the impact of a prior cancer history on thymoma survival has important implications for both decision making and research. Method The Surveillance, Epidemiology, and End Results (SEER) database was queried for thymoma patients diagnosed between 1975 and 2015. Kaplan-Meier methods and Cox proportional hazards model were used to analyze overall survival across a variety of stages, age, and treatment methods with a prior cancer history or not. Results A total of 3604 patients with thymoma were identified including 507 (14.1%) with a prior cancer history. The 10-year survival rate of patients with a prior cancer history (53.8%) was worse than those without a prior cancer history (40.32%, 95%CI 35.24-45.33, P < 0.0001). However, adjusted analyses showed that the impact of a prior cancer history was heterogenous across age and treatment methods. In subset analyses, prior cancer history was associated with worse survival among patients who were treated with chemoradiotherapy (HR: 2.80, 95% CI: 1.51-5.20, P = 0.001) and age ≤ 65 years (HR: 1.33, 95%CI: 1.02-1.73, P = 0.036). Conclusions Prior cancer history provides an inferior overall survival for patients with thymoma. But it does not worsen the survival in some subgroups and these thymoma patients should not be excluded from clinical trials.