Thymic carcinomas have a greater propensity to capsular invasion and metastases than thymomas. Patients more often present with advanced disease and have a 5-year survival rate of 30% to 50%. Owing to the paucity of cases, optimal management of thymic carcinoma has yet to be defined. As with thymoma, in most published series, carefully selected patients with clearly resectable, well-defined disease, have received complete surgical extirpation. For clinically borderline or frankly unresectable lesions, induction chemotherapy, thoracic radiation therapy, or both, have been used.
In most published studies, surgery has been followed by adjuvant radiation therapy. A prescriptive dose range has yet to be identified; most studies use 40 Gy to 70 Gy with standard fractionation scheme (1.8 Gy–2.0 Gy/fraction).
By Darci Picoult
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In the largest series reported to date, data was obtained from 1,320 Japanese patients. The Masaoka clinical stage was found to correlate well with prognosis of thymoma and thymic carcinoma. Patients with thymic carinoma were treated with radiation therapy or chemotherapy. For patients with thymic carcinoma, the 5-year survival rates were 67% for patients treated with total resection, 30% for patients treated with subtotal resection, and 24% for patients whose disease was inoperable. Adjuvant therapy including radiation or chemotherapy did not appear to improve the prognosis in patients with thymic carcinoma.
A multi-institutional retrospective outcome analysis of 186 patients with thymic carcinoma has been reported. This study failed to detect a long-term survival benefit in patients treated with subtotal resection nor any statistically significant survival augmentation from the addition of adjuvant radiation to surgical resection. The authors stipulated that no definitive conclusions could be made regarding the role of adjuvant radiation therapy in thymic carcinoma as a result of sample size limitations.
The 5-year survival rates for patients with totally resected thymic carcinoma were 81.5% for patients treated with chemotherapy; 46.6% for patients treated with radiation chemotherapy; 73.6% for patients treated with radiation therapy alone; and, 72.2% for patients who received no adjuvant treatment.
The results from this study call into question conventional thinking regarding the efficacy of an aggressive multimodality approach including debulking, radiation therapy, and cisplatin-based chemotherapy.[3,4,5] While other studies support the addition of adjuvant radiation and chemotherapy, optimum treatment regimens are undetermined.