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Medline ® Abstract for Reference 92

of 'Epidemiology, classification, clinical presentation, prognostic features, and diagnostic work-up of gastrointestinal mesenchymal neoplasms including GIST'

Prognostic value of KIT/PDGFRA mutations in gastrointestinal stromal tumours (GIST): Polish Clinical GIST Registry experience.
Wozniak A, Rutkowski P, Piskorz A, Ciwoniuk M, Osuch C, Bylina E, Sygut J, Chosia M, Rys J, Urbanczyk K, Kruszewski W, Sowa P, Siedlecki J, Debiec-Rychter M, Limon J, Polish Clinical GIST Registry
Ann Oncol. 2012 Feb;23(2):353-60. Epub 2011 Apr 28.
BACKGROUND: Majority of gastrointestinal stromal tumours (GISTs) are characterised by KIT-immunopositivity and the presence of KIT/platelet-derived growth factor receptor alpha (PDGFRA) activating mutations.
PATIENTS AND METHODS: Spectrum and frequency of KIT and PDGFRA mutations were investigated in 427 GISTs. Univariate and multivariate analysis of relapse-free survival (RFS) was conducted in relation to tumours' clinicopathologic features and genotype.
RESULTS: Mutations were found in 351 (82.2%) cases, including 296 (69.3%) KIT and 55 (12.9%) PDGFRA isoforms. Univariate analysis revealed higher 5-year RFS rate in women (37.9%; P = 0.028) and in patients with gastric tumours (46.3%; P<0.001). In addition a better 5-year RFS correlated with smaller tumour size≤5 cm (62.7%; P<0.001), tumours with mitotic index≤5/50 high-power fields (60%; P<0.001), and characterised by (very) low/moderate risk (70.2%; P = 0.006). Patients with GISTs bearing deletions encompassing KIT codons 557/558 had worse 5-year RFS rate (23.8%) than those with any other KIT exon 11 mutations (41.8%; P<0.001) or deletions not involving codons 557/558 (33.3%; P = 0.007). Better 5-year RFS characterised patients with KIT exon 11 point mutations (50.7%) or duplications (40%). By multivariate analysis, tumours with PDGFRA mutations and KIT exon 11 point mutations/other than 557/558 deletions had lower risk of progression than with KIT exon 11 557/558 deletions (both Ps = 0.001).
CONCLUSIONS: KIT/PDGFRA mutational status has prognostic significance for patients' outcome and may help in management of patients with GISTs.
Department of Biology and Genetics, Medical University of Gdansk, Gdansk, Poland. agnieszka.wozniak@med.kuleuven.be