Expression And Clinical Significance Of Mismatch Repair Genes In Gastric Cancer

Objective:To study the expression and clinical significance of mismatch repair genes in gastric cancer patients,to explore the correlation between the loss of mismatch repair genes and the characteristics of clinical and pathological data in gastric cancer patients,and to provide important guidance for the detection of mismatch repair genes in clinical gastric cancer patients.Methods:A retrospective analysis of 147 patients diagnosed with gastric cancer after operation in the Third Affiliated Hospital of Kunming Medical University from May 2018 to September 2019.Gastric cancer patients were examined by immunohistochemistry for the expression of mismatch repair genes and microsatellite instability.Gastric cancer patients were then tested by polymerase chain reaction.Collect clinical and pathological data of gastric cancer patients,including age,gender,tumor size,tumor location,lymph node metastasis,tumor infiltration depth,tumor differentiation,tumor morphology,EBV,HP infection,Lauren classification,etc.Through SPSS 22.0 software,single factor analysis was used to analyze the correlation between microsatellite stability and microsatellite instability of mismatch repair gene expression.The analysis used ?2 test,and finally defined a P value of less than 0.05 as a statistically significant difference.Results:(1)Collecting 147 cases of gastric cancer patients,IHC detected four mismatch repair gene protein antibodies,14 cases of expression loss showed MSI status,the deletion rate was 9.52%.The independent deletion rates of hPMS2,hMLH1,hMSH2,and hMSH6 were 8.84%,0.68%,4.08%,and 1.36%,respectively.The incidence of MSS,MSI-L,and MSI-H in 147 patients with gastric cancer were 90.47%,4.08%,and 5.44%,respectively.The incidence of pMMR and dMMR in gastric cancer patients were 94.56%and 5.44%,respectively.(2)The MMR gene of gastric cancer patients showed MSI status and age at onset?50 years(?2=4.135,P=0.042),tumor diameter?5(?2=11.097,P=0.001),tumors were located in the gastric antrum and pylorus(?2=4.104,P=0.043),histology of mucinous adenocarcinoma or signet ring cell carcinoma(?2=6.246,P=0.0.044),positive Hp infection(?2=3.994,P=0.046),intestinal type(x2=9.254,P=0.010),Ki-67 positive?40%(?2=4.169,P=0.041)showed significant difference(all P<0.05).MMR gene expression in gastric cancer patients was not related to gender,clinical TNM stage,presence or absence of lymph node metastasis,tumor invasion depth,tumor morphology,nerve and vascular invasion,CEA level,EBV infection,Her-2 expression,and the difference was not statistically significant Significance(P>0.05).(3)MSI-PCR and MMR-IHC detection methods detect about 100%consistency of MSI status;IHC method detects MSI status gastric cancer patients,the proportion of true MSI-H status is low,MSI-PCR and MMR-IHC detection results are correct There is a certain difference in MSI-H status detection(Kappa value=0.182,P=0.231).Conclusions:(1)There is a certain proportion of DNA mismatch repair gene expression loss in gastric cancer patients.MMR gene detection has obvious significance as a screening method for high-risk groups of gastric cancer.(2)Among patients with gastric cancer,those whose DNA mismatch repair(MMR)gene expression is microsatellite unstable(MSI)have the following characteristics:age ?50 years,tumor diameter?5 cm,located in the gastric antrum and pylorus,and histology is mucinous adenocarcinoma Or signet ring cell carcinoma,intestinal type,with Hp infection positive,Ki-67 positive?40%.(3)Inpatients with gastric cancer,the lack of MMR gene expression was not related to gender,clinical TNM stage,presence or absence of lymph node metastasis,tumor invasion depth,tumor morphology,nerve and vascular invasion,CEA level,EBV infection,Her-2 expression,and the difference was not statistically significant significance.(4)The use of MMR-IHC detection method for clinical gastric cancer patients is low cost,short time,simple and practical It can be used as a universal screening method;MSI-PCR method can detect MSI-H status ignored by MMR-IHC detection method,which is MSI screening The gold standard method;MSI-PCR and MMR-IHC detection methods have certain differences in the results of detecting MSI-H status;therefore,the two detection methods can co mplement each other.