Study On The Relationship Between Relative Quantification Of Specific Gut Bacteria And Colorectal Adenomatous Polyps And Colorectal Cancer

Objective:Colorectal cancer is one of the leading causes of cancer-related death,ranking third in incidence and second in mortality among common malignancies worldwide.Colorectal adenomatous polyp is precancerous lesion of Colorectal cancer.Early detection and intervention of adenoma are helpful to decrease the cancer mortality.Enteroscopy is the major diagnosis method of colorectal adenomas and colon cancer.But it is limited due to its invasive operation and cost.Meanwhile,tumor markers and fecal occult blood test are limited due to the lack of specificity.Moreover,their detection rate for several asymptomatic patients with is low.Changes in intestinal microflora are closely related to the occurrence and development of colorectal cancer.Specific intestinal flora such as Fusobacterium nucleatum,Escherichia coli,and enterotoxigenic Bacteroides fragilis have been found to be related with the pathogenesis of colorectal cancer.We will further study whether quantification of intestinal flora is correlated with the stage of adenomas and colorectal cancer.We hope to find relatively specific microbial combination,which can be used to screen groups with high risk,detect colorectal cancer and precancerous lesions in early stage,and provide a basis for the formulation of treatment plans according to the targets of their pathogenesis.Methods:Selecting 69 patients with colorectal adenoma and 55 patients with colorectal cancer up to standard(excluding patients with other gastrointestinal diseases such as inflammatory bowel disease,and acute infectious disease,acute abdomen,diabetes,rheumatoid arthritis,severe liver disease,etc.).During the same period,62 healthy patients were randomly selected as the healthy control group.Fecal specimens were collected and relevant clinical data such as age,sex,BMI,polyp stage,colorectal cancer stage,lymph node metastasis were recorded.Then we measured the relative abundance of Bifidobacterium,Faecaliprausnitzii,enterotoxigenic Bacteroides fragilis,Fusobacterium nucleatum,Parvimonas micra and Escherichia coli with pks gene by Real-time PCR.We compared the differences between the healthy control group and the group with intestinal lesions.In addition,we analyzed the relative abundance of selected bacteria among different stages of colorectal adenoma and colorectal cancer.We also analyzed the correlation between clinical data such as sex,age,BMI,tissue grade of colorectal cancer and the relative abundance of pathogenic bacteria,and evaluated the performance of specific intestinal bacteria as a non-invasive marker of colorectal adenoma and colorectal cancer.Results:1.There is no significance in the relative quantification of Bifidobacterium among the healthy control group,the colorectal adenoma group and the colorectal cancer group.The relative quantification of Faecaliprausnitzii in colorectal cancer group and adenoma group was significantly lower than that in healthy control group.2.The relative quantification of Fusobacterium nucleatum and Parvimonas micra in colorectal cancer group were increased compared with adenoma group and healthy control group.The relative quantification of enterotoxigenic Bacteroides fragilis in adenoma group was significantly higher than that in healthy control group and it was increased at the early stage of adenoma.The relative quantification of Escherichia coli with pks gene in adenoma group have no significant difference compared with healthy control group.3.The relative quantification of Fusobacterium nucleatum,Parvimonas micra and Escherichia coli with pks gene was associated with the stage of tumor.Detection of Fusobacterium nucleatum and Parvimonas micra is expected to be a microbial marker for non-invasive screening or diagnosis of colorectal adenoma and colorectal cancer.Enterotoxigenic Bacteroides fragilis may increase the detection rate of precancerous lesions.4.The ratio of pathogenic bacteria to beneficial bacteria can improve the diagnostic performance of adenoma and colorectal cancer.Conclusions:The structure of intestinal flora in patients with colorectal adenomatous polyps and colorectal cancer has significantly changed,and relative quantification of specific intestinal flora is expected to be one of Biomarkers for screening adenoma and colorectal cancer in non-invasive ways.