Study On Prognosis Evaluation Of Postoperative Chemotherapy For Colorectal Cancer Based On NGS Method

Objective:Colorectal cancer(CRC)is a common malignancy of the digestive system,with one of the highest incidence and mortality rates in the world.The treatment of CRC patients has a significant influence on the efficacy and prognosis.Through the detection of related genes in pathological tissue samples of CRC patients,the correlation between gene mutation and clinicopathological features and prognosis of CRC patients was further studied,so as to provide the evidence for individualized treatment plan and prognosis evaluation of CRC patients after operation.Methods:The subjects were 117 CRC patients(39 females and 78 males)who underwent surgery and chemotherapy in Taizhou people’s Hospital from January 2011 to December 2013.The median age was 65 years old.All patients had complete clinical data and follow-up results.The postoperative chemotherapy regimen was oxaliplatin130mg/m~2intravenous drip for 1 day,oral capecitabine 1000-1250mg/m~2twice a day for 2 weeks,a course of treatment for 3 weeks,and continuous chemotherapy for 6months.The tumor tissue sections of these CRC patients were from the Department of Pathology of Taizhou people’s Hospital.50 genes that play a key role in cell division were detected by next-generation sequencing(NGS).Statistical analysis was carried out by SPSS20.0 software,and the differences between different ratios were compared by Fisher exact test or chi-square test.Med Calc was used to analyze the odds ratio(OR).Mann-Whitney U test was used to compare the difference of continuous variables.Kaplan-Meier curve and log-rank test were used to compare survival data.The risk management regression analysis model of single-factor and multi-factor Cox ratio was established to calculate corresponding 95%confidence interval(95%CI)and the hazard ratio(HR)respectively.P<0.05 was considered statistically significant.Results:1.The driving genes with higher mutation frequency in 117 CRC patients were KRAS,PIK3CA,KIT,MET and EGFR.The positive rates of mutations(taking greater than 0.5%as the threshold of mutation frequency)were 52.1%,29.9%,19.7%,15.4%and 14.5%,respectively.The tumor suppressor genes with higher mutation frequency were TP53,APC,CDKN2A,FBXW7 and STK11.The positive rates of mutation were65.8%,39.3%,32.5%,19.7%and 19.7%,respectively.The mutation frequency of most of KRAS,APC and TP53 tissues was greater than 5%,accounting for 81.9%,73.9%and 72.7%of the mutation frequency of each gene.In most patients with CDKN2A and EGFR mutations,the tissue mutation frequency is less than 5%,accounting for 2.6%and 5.8%of their respective gene mutation frequencies.2.SMAD4 R361C/H,KRAS G12A/C/D/S/V,KIT M541L,MET N375S and IDH1 R132C/H were mutation hotspots in colorectal cancer.The mutation rate of HRAS H27H gene in 117 patients with CRC was 76.9%(OR=5.206,P<0.001),which was a hot spot of synonymous mutation.The mutation rate of PDGFRAV824V gene was 30.7%(OR=1.310,P>0.05).3.TP53 mutations were found in 64 CRC patients over 60 years old,and IDH1gene mutations were found in 13 male CRC patients(P<0.05),indicating that TP53and IDH1 were related to the age and sex of the patients,respectively.4.There were 21 gene mutations in 93 patients with colorectal cancer during follow-up.The main mutation types were TP53,HRAS,KRAS,APC,PDGFRA and PIK3CA,and the mutation frequencies were 40.9%,37.6%,31.2%,24.7%,17.2%and14.0%,respectively.The overall survival time of CRC patients with positive expression of KRAS,PIK3CA,PDGFRA and APC was significantly shorter than that of negative patients(P 0.027;P 0.010;P 0.019;P 0.017).The overall survival time of CRC patients with double negative of KRAS and APC,APC and PIK3CA,KRAS and PIK3CA,PIK3CA and PDGFRA,KRAS and PDGFRA,APC and PDGFRA was significantly longer than that of patients with single positive and double positive(P 0.025;P<0.001;P 0.018;P 0.009;P 0.018;P 0.005).5.Univariate regression showed that APC,KRAS,PIK3CA and PDGFRA were risk factors for the prognosis of postoperative chemotherapy for colorectal cancer(P 0.022;P 0.032;P 0.014;P 0.025).Multivariate regression showed that APC,KRAS,PIK3CA,PDGFRA were independent risk factors for the prognosis of postoperative chemotherapy for colorectal cancer(P 0.008;P 0.048;P 0.013;P 0.005),and there was interaction between KRAS and PIK3CA(P 0.033).Conclusion:1.This study showd that the driving genes with higher mutation frequency in colorectal cancer were KRAS,PIK3CA,KIT,MET and EGFR.The tumor suppressor genes with higher mutation frequency were TP53,APC,CDKN2A,STK11 and FBXW7.These gene mutations may be related to the occurrence of colorectal cancer.2.MET N375S,SMAD4 R361C/H,IDH1 R132C/H,KIT M541L and KRAS G12A/C/D/S/V were mutation hotspots in colorectal cancer.3.PIK3CA,PDGFRA,KRAS and APC were independent risk factors for the prognosis of postoperative chemotherapy in patients with CRC,which were correlated with the survival time of postoperative chemotherapy,and there was interaction between KRAS and PIK3CA.The detection of these gene mutations was helpful to evaluate the efficacy and prognosis of postoperative chemotherapy for colorectal cancer.