MA04.01 Multimodality Treatment and Outcome in Stage III Thymic Epithelial Tumors (TETs): A Retrospective Analysis From the French RYTHMIC Network

Abstract

TETs are rare and potentially aggressive malignancies with high associated prevalence of autoimmune disorders (AIDs). Complete resection, pathological subtype according to WHO classification and Masaoka-Koga stage (MK) are the main prognostic factors. MK III represents a heterogeneous population without a clear optimal therapeutic approach, so we have collected outcomes of patients with MK III TETs in a large prospective registry. RYTHMIC is a French network for TETs composed of national and regional expert centers, with the objective of systematic discussion of patient’s management at a single nationwide tumor board, based on consensual guidelines. We conducted a retrospective analysis of MK III TET patients discussed at the RYTHMIC tumor board between January 2012 and December 2019. Data were prospectively collected in a central database. Prognostic factors for disease-free survival (DFS) and overall survival (OS) were determined by Cox proportional hazards modeling. 366 patients with a median age of 61 years (range 16-90) were included; 52% were male. 27% (n=99) of AIDs, mainly Myasthenia Gravis (n=82, 82.8%). Thymoma B2 was the most frequent (n=106, 29%) followed by B3 (n=71, 19.4%), thymic carcinoma (n=56, 15.3%), AB (n=29, 7.9%), B1 (n=28, 7.7%) and, A (n=22, 6%). Tumor invasiveness were mainly reported to lung (n=99, 27%), pleura (n=91, 25%) and pericardium (n=72, 29.7%). TNM classification was available in 60% of patients, among them: T2 (n=70, 19.1%), T3 (n=135, 36.9%), T4 (n=14, 4%). Forty-two (11.5%) and 23 (6.3%) patients reported phrenic nerve (PN) and great vessels invasiveness, respectively. Surgery was performed in 254 patients (69.4%), resection was complete (R0) in 54% including 34.6% (n=88) PN resection; mean tumor size was 72 mm (1-200 mm) post-operative radiotherapy was delivered to 97% (n=169). Among 55 patients initially considered non-surgical candidates, 36 (65.5%) underwent resection after induction chemotherapy, and 10 (2.7%) patients received with definitive radiotherapy. Recurrence was observed in 87 (26%) patients, mainly to the pleura (n=39, 45%). 10-year OS and DFS were 79% and 30%, respectively. Multivariate analysis for DFS is reported in the table 1; no statistical significance results were found for OS.Table 1Clinicopathological prognostic factors for DFSp-valueHR95% C.I. lower95% C.I. upperSex (female)4,9512,09411,708<0,0001Age at Dx0,9760,9531,0010,059AID0,7910,2952,1230,642T2NANANA0,046T31,4630,5164,1470,474T410,4241,60767,6110,014Type A7,1470,431118,4250,17Type ABNANANA0,982Type B10,2390,0252,2810,214Type B22,3390,6098,9910,216Type B30,7780,1663,6370,749Thymic carcinoma43,187,604245,212<0,0001Complete resection0,3110,140,6920,004Adjuvant Radiotherapy0,7710,2362,5180,666Induction Chemotherapy0,3710,1430,9620,041 Open table in a new tab Complete resection after induction chemotherapy improves recurrence outcome of patients with MK III TET, especially for T4. Adjuvant radiotherapy may have a positive impact on DFS. MK III TET patients not candidates for primary surgery should be systematically reassessed for resection after induction chemotherapy.