Thymic tumors: impact of the TNM for medical oncologists: extended abstract

Abstract

© Mediastinum. All rights reserved. Mediastinum 2022;6:17 | https://dx.doi.org/10.21037/med-21-56 Thymic tumors are rare thoracic malignancies that require comprehensive assessment and multidisciplinary management; these may be aggressive and difficult to treat (1). In the past decade, the scientific community has been increasingly interested in that field, with the creation of many dedicated working groups, including the International Thymic Malignancy Interest Group (ITMIG, www. itmig.org), or local organizations, such as the RYTHMIC (Réseau tumeurs THYMiques et Cancer; www.rythmic. org) network in France. At the 2021 ITMIG virtual annual meeting, a discussion focused on the impact of the 8 TNM classification for medical oncologists. A key point in thymic tumors is that there is no formal clinical staging system, as stage grouping include pathological findings, especially for early stage tumors, and the treatment strategy is then primarily based on whether the tumor may be resected upfront or not, as complete resection represents the most significant prognostic factor on disease-free and overall survival (2,3). Correlation between clinical and final stage is better in advanced stages, given the identification at imaging of vessel invasion, enlarged lymph nodes, pleural/pericardial lesions, or even systemic metastases (4). The management of patients with TETs is based on multidisciplinary expertise that is mandatory at all stages of the disease (1). The assessment of resectability is mostly based on the radiologist and the surgeon expertise, but may be complex, even if the 8th TNM staging provides a definition of resectable anatomical structures (stage IIIA). Ultimately, stage IV disease does not mean that the tumor is not amenable to complete surgical resection, especially in the setting of localized pleural implants (5,6). Multidisciplinary tumor board (MTB) is then recommended at any stage of the disease. In France, RYTHMIC is a nationwide network dedicated to thymic tumors, which was recognized by the French National Cancer Institute, in 2012. The treatment of all patients with TET is discussed on a real-time basis at a national MTB, which is organized twice a month basis using a web-based system. Decisionmaking is based on consensual recommendations, that were originally established based on available evidence, and are updated and approved each year by all members of the network (1). Similar thymoma-dedicated networks are now being implemented in France and in other European countries, such as Spain and Italy (the TYME collaborative group) (7,8). EURACAN is a European Reference Network that helps gathering expertise and organizing initiatives across European countries and expert centers. In Masaoka-Koga stage III/IVA tumors (classified as stage IIIA/IIIB/IVA in the 8 TNM proposed system), complete resection is usually not achievable upfront. A biopsy is performed, followed by primary/induction chemotherapy, in a curative-intent setting with subsequent surgery or radiotherapy (1). Patients not eligible for any kind of local treatment receive definitive chemotherapy. Chemotherapy should be offered as the single modality treatment in advanced, non-resectable, non-irradiable or metastatic (stage IVB) TETs. The aim is to improve tumor-related symptoms through obtention of tumor response, while prolonged survival is uncertain. Cisplatinbased combination regimen should be administered (9-12). No randomized studies have been conducted, and it is Extended Abstract