A prospective epidemiological study of new incident GISTs during two consecutive years in Rhone Alpes region: incidence and molecular distribution of GIST in a European region.

Gastrointestinal stromal tumours (GISTs) are rare tumours of mesenchymal origin arising in the gastrointestinal tract. Incidence data obtained from registries indicate an incidence of approximately 12–15 new cases per million inhabitants per year in western countries (Goettsch et al, 2005; Nilsson et al, 2005); however, there remain uncertainties because of variations in diagnostic criteria before the NCI consensus reported in 2002 (Fletcher et al, 2002). Approximately 95% of GISTs stain positive for CD117 (KIT) and 85% of cases harbour activating mutations in the gene of one of two structurally related transmembrane tyrosine-kinase receptors: KIT and PDGFRA (Hirota et al, 1998; Heinrich et al, 2003a, 2003b; Corless et al, 2005). These activating mutations affect primarily the exons 9 and 11 of KIT, but may also be found on exons 8, 13 and 17 of KIT and exons 12, 14 and 18 of PDGFRA (Heinrich et al, 2003a, 2008; Debiec-Rychter et al, 2006). The relative frequency of the different KIT and PDGFRA mutations in patients with advanced GIST has been previously reported (Heinrich et al, 2003a, 2008; Debiec-Rychter et al, 2006). The frequency of KIT and PDGFRA mutations in localised GIST has been reported in a single-institution study from Italy. Other preliminary reports indicate that PDGFRA mutations may be higher in localised than metastatic GIST, which may reflect their more favourable prognosis. Two recent autopsy series have shown that the incidence of GIST may be as high as 50% in stomach specimens (Kawanowa et al, 2006; Agaimy et al, 2007); in one of these series, canonical KIT or PDGFRA mutations were found in 50% of assessable tumours (Agaimy et al, 2007). We sought to assess the precise incidence of GIST and other sarcomas in the Rhone-Alpes region in France. This report focuses exclusively on GIST.