KIT and PDGFRα mutations in 104 patients with gastrointestinal stromal tumors (GISTs): a population-based study

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BackgroundThe prognostic significance of KIT or platelet-derived growth factor receptor α (PDGFRα) mutations in gastrointestinal stromal tumors (GISTs) is still controversial. Patients and methodsIn all, 104 patients were diagnosed with GISTs by KIT immunoreactivity; tumor DNA was sequenced for the presence of mutations in KIT exons 9, 11, 13 and 17 and in PDGFRα exons 12 and 18. Disease-free survival (DFS) was analyzed in 85 radically resected patients. ResultsKIT mutations occurred in exon 11 (69), in exon 9 (11) and in exon 17 (1). PDGFRα mutations were detected in exon 18 (10) and in exon 12 (3). Ten GISTs were wild type. Exon 11 mutations were as follows: deletions in 42 cases and point mutations in 20 cases and insertions and duplications, respectively, in 2 and 5 cases. A better trend in DFS was evident for duplicated and point-mutated exon 11 KIT GISTs. There was a significant association between PDGFRα mutations, gastric location and lower mitotic index. Moreover, PDGFRα-mutated GISTs seemed to have a better outcome. ConclusionsPoint mutations and duplications in KIT exon 11 are associated with a better clinical trend in DFS. PDGFRα-mutated GISTs are preferentially localized in the stomach and seem to have a favorable clinical behavior.