Management and Long-Term Outcomes of Advanced Stage Thymoma in the United States

Abstract

Thymomas are rare tumors, with limited data regarding treatment of advanced stage disease. Although surgical resection is the mainstay of treatment, the role of additional therapy remains controversial. Our objectives were to describe treatment strategies for stage III/IV thymoma in the United States and compare survival outcomes among treatment approaches. We identified Masaoka stage III/IV thymoma reported in the National Cancer Database between 2004 and 2016. Frequencies of treatment with surgery, chemotherapy, radiation, and combinations were calculated. Five-year overall survival was compared using the Kaplan-Meier method and log-rank test. Risk-adjusted proportional hazards modeling compared mortality between treatment regimens. A total of 1849 patients were identified (1108 stage III, 741 stage IV). Among stage III patients, 83.8% underwent resection (± other modalities) compared with 60.2% of stage IV. Surgery plus radiation was the most common regimen for stage III (32.6%), and nonsurgical treatment (definitive chemotherapy and/or radiation) was the most common for stage IV (36.4%). Overall 5-year survival was 70.3% for stage III and 58.5% for stage IV. In risk-adjusted analysis, surgery plus radiation had the lowest mortality (hazard ratio 0.41, 95% confidence interval 0.30-0.55). Patient age, tumor size, metastases, and non-academic treating hospital were associated with mortality. Current treatment regimens for advanced stage thymoma vary significantly. Regimens that include surgical resection are most common and are associated with superior outcomes. Patients selected to have surgery as primary treatment had the best survival. Adjuvant radiation treatment is associated with better survival and should be considered in patients who undergo resection.