Advanced Thymic Carcinoma: Clinical Experience and Prognostic Factors of 18 Patients

Abstract

Purpose: Thymic carcinoma is an uncommon but lethal malignancy. We analyze the outcomes and prognostic factors of patients with advanced thymic carcinoma treated at a single institution.Materials and Methods: The records of 18 patients with histologically confirmed thymic carcinoma treated between April 1996 and April 2012 at Tri-Service General Hospital were retrospectively reviewed. Surgical resection was performed in 9 patients, including 3 patients who received preoperative therapy and postoperative chemoradiotherapy followed by chemotherapy, 5 who received postoperative chemoradiotherapy followed by chemotherapy and 1 who received postoperative radiotherapy alone. Eight patients had tumor which were unresectable or medically inoperable and underwent chemoradiotherapy followed by chemotherapy or radiotherapy alone. One patient died 2 months after diagnosis without any cancer treatment. Radiotherapy was delivered with three-dimensional conformal radiation therapy, intensity-modulated radiation therapy or stereotactic ablative radiotherapy using Cyberknife (Accuray, Inc., Sunnyvale, CA). The median dose of radiotherapy was 63 Gy. Most (93.3%) of the chemotherapy regimen contained cisplatin.Results: The distribution of Masaoka stage at presentation was III in 7 patients, IVA in 4 patients and IVB in 7 patients. The 5-year overall survival (OS) rate and 3-year progression-free survival (PFS) rate were 46.5% and 32.1%, respectively. The 5-year in-field tumor control rate of 17 patients who underwent radiotherapy was80.9%. Univariate statistical analysis revealed that radiotherapy ≧ 65 Gy was the only statistically significant predictor of outcome. A total radiation dose of ≧ 65 Gy results in improved 3-year OS (100% vs. 13.1%, p= 0.004) and 3-year PFS (47.6% vs. 16%, p=0.044) in patients with thymic carcinoma. The survival benefit of receiving radiotherapy ≧ 65 Gy was apparent in the unresected group of patients with thymic carcinoma.Conclusions: Aggressive multidisciplinary treatments including surgery, radiotherapy, and chemotherapy, are helpful in treating advanced thymic carcinoma. Radiotherapy with dose above 65 Gy may improve the OS and PFS of patients with advanced thymic carcinoma, especially in the unresected group.