Objective To explore the causal relationship between gut microbiota and colorectal cancer,and to investigate whether metabolites have a mediating effect through Mendelian randomization(MR)analysis.Methods Genome-wide association studies data of 473 gut microbiota,233 metabolites,and colorectal cancer were obtained from public databases.Bidirectional MR analyses were performed between gut microbiota,metabolites,and colorectal cancer,respectively.Subsequently,a two-step MR was used to explore whether specific gut microbiota affect the occurrence and development of colorectal cancer through metabolites.Results The study found that the abundances of 7 gut microbiota were positively correlated with the risk of colorectal cancer:Alloprevotella,Atopobiaceae,Clostridium S felsineum,Hungatella,Microvirga,Peptococcia and Ruminococcus A;The abundances of 4 gut microbiota were negatively correlated with the risk of colorectal cancer:Paenibacillales,Prevotella buccae,Psychroserpens and Succinivibrionaceae.Through the two-step mediation analysis,it was confirmed that the ratio of Triglycerides to total lipids ratio in medium very low-density lipoprotein could reduce the impact of Clostridium S felsineum as a risk factor for the occurrence of colorectal cancer.Conclusion The results of this study confirm the causal relationship between some gut microbiota,metabolites,and colorectal cancer,and discover potential interaction chains,providing ideas for the pathogenesis and prevention of colorectal cancer.

Objective To explore the causal relationship between gut microbiota and colorectal cancer,and to investigate whether metabolites have a mediating effect through Mendelian randomization(MR)analysis.Methods Genome-wide association studies data of 473 gut microbiota,233 metabolites,and colorectal cancer were obtained from public databases.Bidirectional MR analyses were performed between gut microbiota,metabolites,and colorectal cancer,respectively.Subsequently,a two-step MR was used to explore whether specific gut microbiota affect the occurrence and development of colorectal cancer through metabolites.Results The study found that the abundances of 7 gut microbiota were positively correlated with the risk of colorectal cancer:Alloprevotella,Atopobiaceae,Clostridium S felsineum,Hungatella,Microvirga,Peptococcia and Ruminococcus A;The abundances of 4 gut microbiota were negatively correlated with the risk of colorectal cancer:Paenibacillales,Prevotella buccae,Psychroserpens and Succinivibrionaceae.Through the two-step mediation analysis,it was confirmed that the ratio of Triglycerides to total lipids ratio in medium very low-density lipoprotein could reduce the impact of Clostridium S felsineum as a risk factor for the occurrence of colorectal cancer.Conclusion The results of this study confirm the causal relationship between some gut microbiota,metabolites,and colorectal cancer,and discover potential interaction chains,providing ideas for the pathogenesis and prevention of colorectal cancer.

Clinical data of 46 patients with trans-sphincter anal fistula treated by fistulectomy with external anal sphincter bareness in Department of Anorectal Surgery, Jiaxing TCM Hospital from July 2018 to July 2019 were retrospectively analyzed. All operations were performed successfully. There were no significant differences in Wexner incontinence scores (2.00±0.68 vs.1.99±0.70, P<0.05), mean anal resting pressure [(75.60±8.60) vs.(73.60±8.20)mmHg(1 mmHg=0.133 kPa), P<0.05] and maximum systolic pressure [(109.60±7.80) vs.(107.20±8.30)mmHg, P<0.05] before and 6 months after operation. There were 1 case with postoperative incision bleeding and 2 cases with postoperative infection. All patients were followed up for 6 months and there was no recurrence and changes in anal shape during the follow-up. Results indicate that the fistulectomy external anal sphincter bareness is safe, efficient with well preserved sphincter function for patients with trans-sphincter anal fistula.