Thymic carcinoma is a rare mediastinal neoplasm with a poor prognosis due to delayed diagnosis and highly malignant behavior. To evaluate 7 serum tumor markers and the outcome of treatment, 11 stage III-IVb thymic carcinomas undergoing multimodality treatment were reviewed. High levels of serum CYFRA21-1 were detected in 5 patients (45%) and correlated with the progression of disease. Of the patients, 6 underwent surgery. The median survival time was 38.4 months, and the 5-year survival rate was 15.6%. The metastatic stage (IVb) and treatment without resection were significantly associated with poorer overall survival (p=0.0034 and p=0.0041, respectively). Our data demonstrated that serum CYFRA21-1 may represent a potential new biomarker in thymic carcinoma. Stage may provide a basis for prognosis in stage III-IVb thymic carcinoma, and resection is one of the most important parts of multimodality treatment for advanced thymic carcinoma. Effective neoadjuvant treatment is therefore essential.