The impact of c-kit mutations on histomorphological risk assessment of gastrointestinal stromal tumors

BACKGROUND: Gastrointestinal stromal tumors (GISTs) are characterized by gain of function mutations of the protooncogene c-kit. We decided to investigate the impact of c-kit mutations on tumor size and mitotic rate, the two most important features for histomorphological risk assessment of GISTs summarized in the Fletcher scheme. METHODS: We examined 43 GIST cases for c-kit mutations in exons 9 and 11 by polymerase chain reaction (PCR) amplification and genomic sequencing. RESULTS: c-kit mutations were detected in 44.2% of the analysed GISTs. In statistical analysis we did not find an effect of c-kit mutations on tumor size and mitotic rate. Furthermore, we detected a slight positive correlation of MIB1 and tumor risk. CONCLUSIONS: We found c-kit mutations variably distributed among all tumor risk groups. Thus, our results showed that c-kit mutation analysis was not a helpful instrument in routine histomorphological risk assessment of GISTs based on the Fletcher classification.