This observational case-control study aims to compare the composition of intestinal microbiota between colorectal cancer (CRC) patients and healthy individuals. Fecal samples from 36 CRC patients and 25 healthy controls were analyzed for bacterial abundance. Results indicate significant differences in beneficial, neutral, and harmful bacterial populations between groups, with CRC patients showing reduced beneficial flora (e.g., Lactobacillus) and increased harmful/neutral flora (e.g., Staphylococcus). Further stratification by cancer stage (I-III) revealed progressive dysbiosis with disease progression.

This observational case-control study investigates the compositional differences in intestinal microbiota between individuals diagnosed with colorectal cancer (CRC) and healthy controls. The study enrolled 36 CRC patients confirmed by histopathology and 25 age- and gender-matched healthy volunteers without gastrointestinal diseases or antibiotic/probiotic use within the preceding three months. Fecal samples were collected from CRC patients at the time of diagnosis and from healthy participants during routine health screenings. Utilizing 16S rRNA sequencing or quantitative PCR, the relative abundance of specific bacterial taxa (e.g., Lactobacillus, Bifidobacterium, Staphylococcus) was quantified to assess dysbiosis patterns. Additionally, the analysis stratified CRC patients by clinical stage (I-III) to explore progressive shifts in microbial communities with disease advancement. The findings aim to elucidate the role of gut microbiota in CRC pathogenesis and provide insights into potential microbiome-based diagnostic or therapeutic strategies.

Inclusion Criteria:

• Adults (≥18 years) with histopathologically confirmed colorectal cancer (CRC group)
• Archived fecal sample available from time of CRC diagnosis (prior to treatment)
• Complete clinical records including TNM staging (I-III) for CRC patients
• Age- and gender-matched adults without CRC history (control group)
• Archived fecal sample available from routine health check-ups (control group)

Exclusion Criteria:

• Recent antibiotic or probiotic use (within 3 months)
• History of inflammatory bowel disease
• Incomplete medical records
• For controls: history of colorectal cancer, polyps, or chronic gastrointestinal diseases
• For controls: abnormal colonoscopy or fecal occult blood test within the past year

Retrospective case-control study of 36 CRC patients (stages I-III, diagnosed 2022-2023) and 25 healthy controls from Central Hospital, Zhanjiang, China. CRC group: pre-treatment fecal samples, TNM staging. Control group: age/gender-matched, no GI diseases, normal colonoscopy/fecal tests. Exclusions: antibiotic/probiotic use (past 3 months), inflammatory bowel disease, incomplete records.

Individual participant data will not be shared publicly due to restrictions imposed by the hospital ethics committee and Chinese data privacy laws.