Postoperative Adjuvant Chemotherapy for Thymic Cancer (FUSCC-Thymic 3)

The goal of this clinical trial is to learn the role of adjuvant chemotherapy for patients with thymic carcinoma and completed resection. The main questions it aims to answer are: 1. Does adjuvant chemotherapy decrease disease progression? 2. Does medium dose of three drugs (paclitaxel, cisplatin, 5-FU) well tolerance? Researchers will compare chemoradiotherapy to radiotherapy to see whether chemoradiotherapy could decrease disease progression or not. Participants will: 1. Take radiotherapy (50Gy/25f) with or without 4 cycles of chemotherapy (TPF). 2. Follow up every 3 months in the first two year, and then every 6 months.