Rare cancersRare cancers are associated with poor survival, accounting for 22% of new cancer diagnoses in Europe, and 30% of cancer deaths. Sarcomas are a heterogeneous group of life-threatening rare solid malignancies affecting soft and bone tissues, representing 10% of rare tumors and around 2% of adult tumors, with an incidence of 5.9/100,000/year in Europe. Appropriate management of sarcoma patients is hindered by the absence of referral policies to reference centers (RCs), incorrect or delayed diagnosis, non-adherence of therapies to clinical practice guidelines (CPGs), and lack of expertise by practitioners, which increases the risk of relapse and death. These problems worsen in the Community of Latin American and Caribbean States (CELAC) due to the scarcity or complete unavailability of RCs, expert pathologists, multidisciplinary tumor boards (MTBs), new cancer drugs, clinical trials, patient registry data, and financial resources. Hence, the SELNET project seeks to create a European and Latin American multidisciplinary network of clinical and translational specialists to improve diagnosis and clinical care in sarcomas, with the aim of validating a collaborative model replicable in other rare tumors and in other countries. Recognized cancer centers and research groups of Spain, Italy, France, Mexico, Brazil, Argentina, Costa Rica, and Peru will contribute to better rare cancer care by fostering RCs, healthcare barrier analysis, CPGs, and medical education as key improvement drivers. The core of the research work focuses on improving diagnosis and prognosis of sarcoma patients through the creation of pathological diagnosis networks, MTBs, the conduct of an international registry-based observational study to assess clinical management quality and prognostic factors, and the implementation of an strategic translational research program to develop intercontinental sarcoma biobanks, preclinical models, and a translational study with drugs in rare sarcoma subtypes.