Establishment of threshold of human gut microbes and risk assessment system for colorectal cancer.

A total of 218 CRC-associated bacteria and 15 gut microbial characteristics were identified through literature review and analysis.

• The 15 gut microbial characteristics included enterotypes and Firmicutes/Bacteroidetes ratio among others.
• CRC-related bacteria and gut microbial characteristics were screened by literature review.
• These 218 bacteria and 15 characteristics formed the basis for threshold development.

A 5–95% threshold was established for 218 CRC-associated bacteria and 15 gut microbiome signatures to define the normal range of gut bacteria.

• Reference ranges were derived from 8021 fecal samples from healthy people and 497 from CRC patients collected from public databases.
• The 5–95% medians of gut microbial characteristics in healthy populations were used as reference values.
• This represents the first quantitative threshold established for CRC-associated bacteria.

The study used two sequencing platforms to detect stool DNA sequence in CRC and healthy subjects.

• 16S rRNA Miseq sequencing was performed on 175 CRC patients and 175 healthy people.
• PacBio sequencing was performed on 200 CRC patients and 200 healthy people.
• Community composition of gut microbiota between CRC and healthy subjects was plotted and species differences were analysed by Lefse analysis.

A CRC evaluation intelligent system software was developed that can calculate values for 218 CRC-related bacteria and 15 gut microbial characteristics and assess whether they fall within established thresholds.

• The software processes sequencing data to rapidly calculate values for all 218 CRC-related bacteria and 15 gut microbial characteristics.
• The software includes a function for predicting CRC risk.
• The software assesses whether individual values are within the established threshold ranges.

The CRC risk assessment system achieved accuracy ranging from 89.14% to 91.50%.

• Accuracy was evaluated using both 16S rRNA Miseq sequencing data and PacBio sequencing data.
• R studio software was used to analyse CRC-related bacteria and gut microbial characteristics.
• The accuracy range of 89.14% to 91.50% was reported across assessment conditions.