The analysis of status and clinical implication of KIT and PDGFRa mutations in gastrointestinal stromal tumor (GIST).

10562 Background: To investigate the status of KIT and PDGFRA mutations in the gastrointestinal stromal tumors (GIST) and its clinical implication in China.,141 GISTs were evaluated for the presence of KIT and PDGFRA mutations. Exon 9, 11, 13, 17 of KIT and exon 12, 18 of PDGFRA were analyzed by PCR amplification and direct sequencing. The clinical features, prognostic factors, mutational status and their relationships were analyzed with statistical tools in this study.,Generally, KIT mutations were identified in 76.6% (108/141) in all our 141 GISTs: 70.2% (99/141) involving exon 11, 5.7% (8/141) involving exon 9, 0.7% (1 /141) involving exon 13 and no mutation detected in exon 17. The gene mutations were mostly heterogeneous. The KIT exon 11 mutational format included deletion (65.7%), point mutation (24.2%) and insert duplications (10.1%). The mutations clustered in the classic "hot spot" at the 5|o:end of the exon mostly heterogeneous and the second "hot spot" were internal tandem duplications (ITD) at the 3'end of the exon. PDGFRA mutations were totally identified in 12.1% (4/33) of no-KIT-mutation GISTs and 40% (4/10) of CD117- negative GISTs: all involving exon 18 with the mutations D842V. With the analysis between clinical features and mutation status, we found the significant difference of gene mutation rate in the different primary tumor organs (x2=7.229, p=0.027; x2=7.000, p=0.03).The overall mutation rate in the GIST originated from colorectum or extra-gastrointestinal tract was lower than that from stomach and small intestinal and the difference is significant (x2=6.728, p=0.009; x2=4.059, p=0.044). The ckit exon11 mutation rate in the gastric stromal tumors is higher than that in the other sites and the difference is significant (x2=5.713, p=0.017; x2=4.341, p=0.037). The mutation rates, whatever overall mutation rate or ckit exon11 mutation rate, were no significant differences between the groups of age, gender, tumor size, mitotic rate, grade of malignant potential and liver metastasis or not.,Most GIST had the KIT or PDGFRA gene mutation. There was significant difference between gene mutation rate and primary tumor organ in China. No significant financial relationships to disclose.