• Sarcomas represent 1% of all cancers and 4,000 new cases a year in France.
• Sarcomas are a group of heterogenic tumours, clinically and histologically, and regarding their prognosis.
• They develop from the tissues that support the body (muscles, bones, adipose tissue, nerves, etc.). A distinction is made between the sarcomas of “soft tissues” which include the viscera and bone sarcomas.
• There are at least 150 different subtypes with liposarcomas, leiomyosarcomas, fibrosarcomas, angiosarcomas, GIST, osteosarcomas, and so forth. They can affect many parts of the body (limbs, torso, neck, etc.).
• They are subject to a new WHO classification dating from 2013.
• According to their type, they can affect persons of all ages, from children to the elderly.
• They are now better understood thanks to the progress made in molecular biology.
• Very often, they present genetic abnormalities: translocation, amplification, inactivation, mutation or rearrangement. Researchers specialised in the study of sarcomas have discovered and are still discovering abnormalities specific to one or more sarcomas. Their findings can improve the diagnosis of these tumours and lead to the development of more targeted therapies.
Advances: At the end of 2015, two teams of the Inserm (Centre Léon Bérard and the Institut Curie) highlighted a new genetic variant of sarcomas, the “SMARCA4-deficient thoracic sarcoma”. Their results, published in Nature Genetics, permit better diagnosis for this cancer and thus speed up the care process. The researchers validated a biomarker, SOX2, overexpressed by this new cancerous entity. Prof. Jean-Yves Blay, the co-director of this study, founder of the WSN and member of the Management Board of Lyon Synergy Cancer, declares, “Our priority is to refine the classifications of tumours used in clinical practice in order to provide patients with a more adapted therapeutic choice”. Molecular investigations have demonstrated inactivations of the SMARCA4 gene in twenty samples of sarcomas with similar clinical and pathological characteristics. SMARCA4 codes for the BAF complex, which participates in the regulation of chromatin structure. It presents modifications in 1 cancer out of 5 and is now the subject of research on its therapeutic targeting.
• 40% of sarcomas can now be characterised by a specific modification of DNA during examination by anatomical pathology.
• According to WHO, up to 20% of sarcomas have not yet been classified.
• Diagnosis problems persist for about 15% of sarcomas, even following review by a panel of anatomical pathology experts.