Abstract: Objective To detect the PIK3CA gene mutation in Chinese gastric cancer, and analysis the clinical value . Methods Fluorescence PCR was used to screen the positive case of gastric cancer PIK3CA genes mutated and Sanger DNA sequencing method was used to detect the hotspot mutation regions of PIK3CA, Analysis the relationship between the gene mutation and clinicopathological character. Results PIK3CA gene mutations were detected in 7.5% (30/400) of tumor samples, and the gene mutation position mainly focused on exon 9（E542K，E545K） and exon 20（H1047R， H1047L）, the gene mutation of PIK3CA seemed to be closely related with the prognosis（P<0.05）,but not with the size of tumor, pathological grade, lymph node metastasis and the age of patient. Conclusion The rate and the hotspot mutation regions of PIK3CA in gastric cancer among Chinese is unique, PIK3CA gene mutation might be an important indicator to evaluate gastric cancer prognosis and a new target for tumor gene therapy.

Key words: PIK3CA, gastric cancer, prognosis, fluorescence PCR