Application Of Fecal DNA Methylation Detection In Early Screening Of Colorectal Cancer

Background: Colorectal cancer is a disease that has received widespread attention worldwide,and its annual increasing incidence has forced us to diagnose the disease early and accurately.The presence of a tumor-specific DNA methylation pattern in colorectal epithelial cells that are shed in human feces provides a simple,non-invasive screening test for colorectal cancer and its precursor--adenoma.Purpose:This study investigated the positive rate of three genes for detecting colorectal cancer and adenoma,and evaluated the value and application prospects of fecal DNA methylation in early detection and diagnosis of colorectal cancer.Method:Collecting 136 fecal samples with colorectal cancer,adenoma and normal controls before the resection of polyps or tumors in Suzhou Municipal Hospital from2017 to 2019.Obtaining tumor or adenoma tissue by endoscopy to the pathology department for pathology analyze and mark the location and size of the lesion.Fecal samples were subjected to quantitative methylation analysis by methylated-specific PCR(MSP)in the laboratory,and three different gene promoters of ELMO1,RIMS1,and IKZF1 were methylated in the stool of different grouped patients.The positive rate,sensitivity and specificity of promoter methylation of ELMO1,RIMS1 and IKZF1 in different groups of patients were calculated,and their relationship with relevant clinical data was analyzed to evaluate its early screening as colorectal tumor.Check the efficacy of the indicator and its superiority compared to traditional early screening methods and Fecal Occult Blood Testing(FOBT).Result:In this experiment,a total of 136 patients were collected from the hospital,and the final sample of the successful human β-actin fragment was 114 cases,including 20 cases of colorectal adenocarcinoma,59 cases of adenomatous polyps,and 35 cases of normal hospitalized patients.The positive rates of methylation of ELMO1,RIMS1,and IKZF1 in colorectal cancer were 80.0%,85.0%,and 80.0% respectively,and the positive rates in advanced adenomas were 30%,50%,and 70%.When the three genes were combined,The positive rate of joint detection of adenoma was 67.8%,the positive rate of combined detection of colorectal tumor was 90%,the specificity was55.3%.In the fecal DNA of the normal control group,the methylation positive rates of ELMO1,RIMS1,and IKZF1 gene promoters were 2.86%,2.86%,and 0%.There was no correlation between the methylation status of ELMO1,RIMS1 and IKZF1 gene promoters in colorectal cancer fecal DNA and the age,sex,tumor location and Dukes stage of colorectal cancer patients.In 20 patients with colorectal tumors,9cases of fecal occult blood positive,the positive rate was 45%,59 cases of adenoma patients,fecal occult blood positive 2 cases,the positive rate was 3.39%,and fecal DNA methylation detection The positive rates were 90% and 67.8%,respectively.Compared with FOBT,the positive rate was higher,and the difference was statistically significant(P<0.01).Conclusion:The methylation of ELMO1,RIMS1 and IKZF1 genes showed a high positive rate and specificity in the detection of colorectal cancer.It has certain reference value in detecting colorectal adenoma,especially the positive detection of IKZF1 gene is high,which is helpful for finding precancerous lesions.Compared with the traditional fecal occult blood test,the fecal DNA test has obvious advantages to detecte the colorectal cancer and precancerous lesions(adenomas).Fecal DNA testing is expected to be an early screening method for colorectal cancer and precancerous lesions and is likely to be commonly used.