FP05.04 Outcomes of Resected Thymic Epithelial Tumors (TET), insights from RYTHMIC

IntroductionTET are rare malignancies, with an annual incidence of 350 cases in France. The main prognostic factors are Masaoka-koga stage and quality of the resection. However, no large cohorts have been published concerning resection outcomes. RYTHMIC (Réseau tumeurs THYMiques et Cancer) is a French network mandated to systematically discuss every case of TET. We aimed to describe the resected tumor outcomes in a large French population.MethodsRYTHMIC database, hosted by IFCT (Intergroupe Francophone de Cancérologie Thoracique), prospectively includes all consecutive pts with a diagnosis of TET discussed in French national or regional tumor boards. We analyzed epidemiologic, clinical and pathological characteristics of 1045 pts operated of a TET.ResultsFrom January 2012 to December 2019, 2909 pts were included in the database. Overall, the median age at diagnosis of TET was 60 (range 9-90) and 52% (n=1513) were male. Of them, 1082 (37,2%) pts were operated. 304/1045 (29%) pts reported autoimmune disorders and Myasthenia Gravis was the most common (250 pts, 82,2%). Masaoka-Koga stages (MK) were well balanced with 23% (n=240) stage I, 17.2% (n=180) stage IIa, 18.2% (n=190) stage IIb, 19.6% (n=205) stage III with lung as a main invaded organ (37%), 8% (n=85) stage IVa and 4.9% (n=51) stage IVb. Among resected tumors, B2 and AB were the most common subtypes (n=247, 23.6% and n=237, 22.7% respectively). Sternotomy was the most used approach for resection (n=735, 70.3%). In addition to TET, surgery was extended to lung (35%), pericardium (24%), pleura (13%), recurrent nerve or great vessels (10%) and lymph nodes (46%). Complete resection was assessed in 71% of procedures with a median tumor size of 55mm (1-260) and a range of 0-28 resected pleural metastasis. Intrapleural chemotherapy was used as an associated technique during the first-line surgery (6/17 pts) or after recurrence (9/17 pts, 53%) shrinking the hazard for progression (PD) (OR= 0.5 95%CI [0.29 to 0.84], p