IA05.02 Mesothelioma Cases

Abstract

Malignant pleural mesothelioma (MPM) is a highly lethal malignancy arising from the serosal lining of the pleural cavity.1 In up to 80% of patients, asbestos is considered to contribute to the development of this tumor within about 20 to 40 years of exposure time.2 The incidence of MPM is expected to increase dramatically over the next few decades. It has been estimated that 250 000 people will die of MPM in Europe in the next three decades, and 2500–3000 new cases are diagnosed each year in the USA.3 The macroscopic appearance of MPM depends on disease stage. In early stage MPM, the cancer presents as multiple small nodules on the surface of both pleural linings. In advanced stages, the multiple small nodules form a tumor plate which surrounds the lung like a cage and in most cases invades the lung parenchyma, diaphragm and pericardium.4 The establishment of the pathological diagnosis of MPM and the classification in three main histological subtypes (namely epitheloid, biphasic and sarcomatoid) is important and has an impact on therapy and prognosis. Epitheloid MPM is more therapy responsive and associated with better outcome compared to biphasic and sarcomatoid histotypes. Other very important simple prognostic factors for MPM are disease stage and lymph node involvement. Therefore an adequate staging of MPM patients is crucial for therapy decision-making. The currently widely used staging system is the one according to International Mesothelioma Interest Group (IMIG) established in 1996.5 Based on the TNM (tumor-node-metastasis) system for malignant tumors, this staging system describes: the extent and size of the primary tumor, lymph node involvement and distant metastases. By the different TNM descriptors, MPM can be classified and summarized in four different tumor stages (IMIG I-IV). Patients suffering from stage I-III are considered for surgery within multimodality protocols, while palliative systemic or local treatment is indicated for stage IV in accordance with the current classification. Butchart et al.6 proposed in 1976 an alternative staging system, referred to as the Butchart Staging. Contrary to the IMIG system (based on lung cancer staging) the Butchart system is particularly set up for MPM. Therefore, several differences between both staging systems exist. However, the IMIG in collaboration with the International Association for the Study of Lung Cancer (IASLC) have proposed a new T, N and M descriptors for in the forthcoming 8th edition of the TNM classification for MPM with significant changes to the 7th TNM edition and proposals have been very recently published.7-9 With regard to the T descriptor, a fusion of both, clinical and pathological T1a and T1b into a T1 was recommended.7 Regarding the N descriptor, a summary of the clinical and pathological N1 and N2 categories into a single category with the classification into ipsilateral, intrathoracic nodal metastases (N1) was proposed.8 No changes have been recommended for the M descriptor in the 8th edition of the TNM.9 In this presentation, 4 patient cases of different stages of MPM patients will be presented and the newly proposed TNM descriptors and IMIG staging will be applied. Cases and changes in the staging system will be discussed together with the attending audience in an interactive manner. After the presentation, the participants will be able to understand and practically apply the forthcoming changes in the TNM system for staging of MPM patients. 1. Whitaker, D., J.M. Papadimitriou, and M.N. Walters, The mesothelium and its reactions: a review. Crit Rev Toxicol, 1982. 10(2): p. 81-144. 2. Lanphear, B.P. and C.R. Buncher, Latent period for malignant mesothelioma of occupational origin. J Occup Med, 1992. 34(7): p. 718-21. 3. Peto, J., et al., The European mesothelioma epidemic. Br J Cancer, 1999. 79(3-4): p. 666-72. 4. Rudd, R.M., Malignant mesothelioma. Br Med Bull, 2010. 93: p. 105-23. 5. Rusch, V.W., A proposed new international TNM staging system for malignant pleural mesothelioma from the International Mesothelioma Interest Group. Lung Cancer, 1996. 14(1): p. 1-12. 6. Butchart, E.G., et al., Pleuropneumonectomy in the management of diffuse malignant mesothelioma of the pleura. Experience with 29 patients. Thorax, 1976. 31(1): p. 15-24. 7. Nowak, A.K., et al., The IASLC Mesothelioma Staging Project: Proposals for Revisions of the T descriptors in the forthcoming Eighth edition of the TNM classification for pleural mesothelioma. J Thorac Oncol, 2016. 8. Rice, D., et al., The IASLC Mesothelioma Staging Project: Proposals for Revisions of the N Descriptors in the Forthcoming Eighth Edition of the TNM Classification for Pleural Mesothelioma. J Thorac Oncol, 2016. 9. Rusch, V.W., et al., The IASLC Mesothelioma Staging Project: Proposals for the M Descriptors and for Revision of the TNM Stage Groupings in the Forthcoming (Eighth) Edition of the TNM Classification for Mesothelioma. J Thorac Oncol, 2016. Staging, TNM, Mesothelioma