Les tumeurs thymiques : traitements systémiques et place de la radiothérapie

Abstract

Thymic epithelial tumors are rare malignancies, that may be aggressive and difficult to treat, with variable prognosis. The histopathological classification distinguishes two major tumor types: thymomas and thymic carcinomas. Autoimmune manifestations are observed in nearly one third of patients at diagnosis; myasthenia gravis is the most common, followed by pure red cell aplasia and hypogammaglobulinemia. The historical staging system is the Masaoka system, reviewed by Koga; the 9th TNM system is standard since 2025. Assessment of resectability is the first step in the treatment of a thymic tumour, even at an advanced stage; even in advanced cases, complete resection remains the most significant prognostic factor for patient survival. If complete resection seems possible from the outset, surgery is the first stage of treatment, possibly supplemented by postoperative radiotherapy. In the case of unresectable thymic tumours, a pre-therapeutic biopsy should be performed for diagnostic purposes. The treatment strategy is based on induction chemotherapy followed by surgical resection or irradiation. Patients who remain ineligible for focal treatment receive chemotherapy exclusively. More targeted therapies would appear to be of interest as a subsequent line of treatment, as would immunotherapy in the context of thymic carcinoma, although toxicity needs to be monitored very regularly. Following an INCa call for tenders in 2010, a national care network of expert centres for thymoma and thymic carcinoma was set up in 2012: the RYTHMIC network (Thymic Tumours and Cancer Network). This network provides answers to very specific diagnostic or therapeutic questions in the context of rare tumours, as well as collating information on treatment to help improve it in the future.