Simple SummaryA Gastro-Intestinal Stromal Tumour (GIST) is a rare type of cancer discovered in the last decades of the 20th century and whose characteristics are still being defined. Knowledge of the distribution of any disease and its severity among a population is paramount for the best distribution of efforts and resources intended for its diagnosis and treatment. The present study was started by the European Union Joint Action on Rare Cancers and is aimed at shedding light on the current status of GISTs in a region in the southeast of Spain, the matter being quite unknown in the whole of Europe because of there being few previous studies and partial invalidation of those studies due to prior consideration of some subgroup of GIST as non-cancerous. Aside from producing useful information for health authorities, our study will contribute to expanding the knowledge of this relatively new and, from a population level point of view, poorly known cancer.AbstractGastro-Intestinal Stromal Tumours (GISTs) are a kind of neoplasm whose diagnosis in common clinical practice just started in the current century, implying difficulties for proper registration. Staff from the Cancer Registry of Murcia, in southeastern Spain, were commissioned by the EU Joint Action on Rare Cancers into a pilot study addressing GIST registration that also yielded a population-based depiction of GISTs in the region, including survival figures. We examined reports from 2001 to 2015 from hospitals as well as cases already present in the registry. The variables collected were sex, date of diagnosis, age, vital status, primary location, presence of metastases, and risk level according to Joensuu’s Classification. In total, 171 cases were found, 54.4% occurred in males, and the mean age value was 65.0 years. The most affected organ was the stomach, with 52.6% of cases. Risk level was determined as “High” for 45.0%, with an increment of lower levels in recent years. Incidence for the year 2015 doubled that of 2001. Overall, the 5-year net survival estimation was 77.0%. The rising incidence magnitude is consistent with trends in other European countries. Survival evolution lacked statistical significance. A more interventional approach in clinical management could explain the increase in the proportion of “Low Risk GISTs” and the first occurrence of “Very Low Risk” in recent years.