Preoperative induction therapy for locally advanced thymic tumors: a retrospective analysis using the ChART database

Yucheng Wei, Zhitao Gu, Yi Shen, Jianhua Fu, Liejie Tan, Members of the Chinese Alliance for Research in Thymomas, Yongtao Han, Chun Chen, Renquan Zhang, Yin Li, Keneng Chen, Hezhong Chen, Yongyu Liu, Youbing Cui, Yun Wang, Liewen Pang, Zhentao Yu, Xinming Zhou, Yangchun Liu, Yuan Liu, Wentao Fang, Members of the Chinese Alliance for Research in Thymomas


Background: To evaluate the role of preoperative induction therapy on prognosis of locally advanced thymic malignancies.
Methods: Between 1994 and 2012, patients received preoperative induction therapies (IT group) in the Chinese Alliance for Research in Thymomas (ChART) database, were compared with those having surgery directly after preoperative evaluation (DS group). All tumors receiving induction therapies were locally advanced (clinically stage III-IV) before treatment and those turned out to be in pathological stage I and II were considered downstaged by induction. Clinical pathological characteristics were retrospectively analyzed. To more accurately study the effect of induction therapies, stage IV patients were then excluded. Only stage I-III tumors in the IT group and stage III cases in the DS group were selected for further comparison in a subgroup analysis.
Results: Only 68 (4%) out of 1,713 patients had induction therapies, with a R0 resection of 67.6%, 5-year recurrence of 44.9%, and 5- and 10-year overall survivals (OS) of 49.7% and 19.9%. Seventeen patients (25%) were downstaged after induction. Significantly more thymomas were downstaged than thymic carcinomas (38.7% vs. 13.9%, P=0.02). Tumors downstaged after induction had significantly higher 5-year OS than those not downstaged (93.8% vs. 35.6%, P=0.013). For the subgroup analysis when stage IV patients were excluded, 5-year OS was 85.2% in the DS group and 68.1% in the IT group (P=0.000), although R0 resection were similar (76.4% vs. 73.3%, P=0.63). However, 5-year OS in tumors downstaged after induction (93.8%) was similar to those in the DS group (85.2%, P=0.438), both significantly higher than those not downstaged after induction (35.6%, P=0.000).
Conclusions: Preoperative neoadjuvant therapy have been used only occasionally in locally advanced thymic malignances. Effective induction therapy leading to tumor downstaging may be beneficial for potentially unresectable diseases, especially in patients with thymomas. These findings would be helpful to related studies in the future.