The management of rare cancers is controversial. The role of adjuvant therapies, such as chemotherapy and radiation therapy remains unclear. The limited number of patients included in the studies cannot generally allow any consistent statistical analysis to determine either prognostic factors or the impact of surgery and adjuvant therapies on local control and long-term survival. The Rare Cancer Network is a multi-institutional cooperative group created in 1993 to initiate large retrospective studies on rare cancers with the aim of improving our knowledge in terms of management, outcome, and prognostic factors of such tumors. The network gathers more than 70 institutions from 21 countries. So far, 32 projects have been carried out. In this report we will discuss the most significant data provided by our group in several investigated diseases.