PC03.07 Adjuvant Chemotherapy for Thymic Carcinoma - YES

Abstract

The role of postoperative treatment in thymic carcinoma is still a controversial issue, because of the low level evidence supporting clinical management of this cancer, made of cohort studies, retrospective studies and case reports, but no randomized clinical trials. Stage is not the only factor we should consider when the choice of postoperative chemotherapy is discussed; completeness of resection and histologic subtype have their own relevance. Thymic carcinoma accounts for about 20% of all thymic cancers, most cases diagnosed as Masaoka-Koga stage III. In this scenario, about 60% of the cases relapse at 10 years. Time of relapse and sites of disease progression should be carefully reviewed when we consider potential benefit of postoperative systemic treatment; thymic carcinomas relapse earlier and commonly at distant sites compared with thymoma, with significantly different 5 years overall survival and progression free survival. Histology preserves its association with progression free survival as radicality of resection. One reason for the controversies about the prognostic role of histology itself may be found in the difficult diagnosis of the specific subtypes as defined by WHO. Across series a complete Interobserver agreement was reported in 10 to 50% of the cases. Most difficulties seem to be the differential diagnosis among B tumors, and a better agreement was achieved when B2-B3 thymoma were grouped together with carcinoma, suggesting overlapping features among them and supporting evidence that type B3 thymomas and thymic carcinomas form a biologically different group. Complete resection of thymic carcinoma is possible in 60%-70% of the cases, achieving 5-Y and 10Y survival of 60% and 40% respectively. Type of resection and Masaoka stage seem to be correlated with survival and cumulative incidence of recurrences. However, a prognostic role of adjuvant treatment, particularly radiotherapy, is shown with possible effect not only in overall survival but also in relapse free survival. On the basis of the available data, it would be tempting to suggest a possible role for chemotherapy in R1-R2, independently by stage, preferably associated with radiation. On the other hand guidelines suggest a role for adjuvant chemotherapt in resectable thymic carcinoma R1 and, in R0 cases, in stage III or in those cases become resectable after induction chemo, independently by stage e type of resection, especially if not received before. The upcoming IASLC/ITMIG staging system, which re-defines Masaoka-Koga stage III downstaging some situations to stage I and II (as mediastinal pleural or pericardial involvement) could potentially influence adjuvant chemo in stage III thymic cancer. Stage III will be distinguished into T3, potentially resectable upfront, and T4, which might need induction chemo. Adjuvant chemoregimens may be chosen on the basis of drugs combinations effective in the palliative setting; platinum-based doublet plus etoposide or taxanes, or multiple drug regimens including anthracycles are the most used, no data favoring one regimen over the others. Response rates among 60 to 100% in main phase II trials are reported, with primary chemotherapy alone or plus concomitant radiotherapy, in all thymic malignancies. Higher response rates with anthracycles in thymoma and cisplatin in thymic carcinoma are suggested by literature evidence. Adjuvant; thymic carcinoma; stage