[To answer rare cancer issues. Geographical analysis of EMS sarcoma cohort in the Rhône-Alpes region].

Rare cancer issues have not been much explored yet because of their low incidence. That is why epidemiological studies have difficulties in identifying indisputable etiological risk factors. An expert opinion, mainly concentrated in some establishments, is required for these cancers' management. However, on account of the potential remoteness of these therapeutic resources, the patients' way of care remains also unstudied. By means of a geographical analysis of a regional exhaustive cohort of sarcoma, diagnosed in 2006 and 2007 and followed during five years at least, we can make progress on these different issues. Gastro-Intestinal and Stromal Tumors (GIST) occur more frequently in privileged territories while liposarcomas arise in more deprived areas. The association between liposarcomas and areas deprivation is significant (P=0.05). Moreover, pre-operative biopsy and some clinical patient characteristics, age, grade or tumor localization, are associated with an increase in the distance covered by patients for the first-line treatment (p ≤ 0,001). In the scope of an interdisciplinary collaboration, the geographical approach develops some hypothesis for rare cancers research, which must be tested by other larger scale studies.