Association of

Background: Colorectal cancer (CRC) is one of the primary causes of cancer-associated deaths worldwide, and growing evidence shows that alteration in the gut microbiota may be a contributing factor to the development and progression of the disease. This study investigates the correlation between CRC and specific intestinal microbiota abundance, including Firmicutes, Lactobacillus, Enterococcus, Clostridium, and Bifidobacterium. Material and methods: In this study, 100 CRC samples and adjacent normal tissues were obtained from Iranian patients. Afterward, we assessed the abundance of the mentioned bacteria in matched tumor and normal tissue samples from 100 CRC patients, by TaqMan quantitative real-time polymerase chain reaction (qPCR). Results: Most of the patients (55 %) had grade II cancer (moderately differentiated), followed by grade III (poorly Differentiated) in 19 %, and the distribution of the tumor location was 65 % in the colon and 35 % in the rectum. Our research showed a substantial difference in the relative abundance of specific bacteria in tumors and healthy tissues. To this end, four genera of bacteria, including Bifidobacterium, Lactobacillus, Clostridium, and Firmicutes, exhibited statistically significant reductions in tumor tissues compared to adjacent normal tissue (p < 0.05). Conversely, Enterococcus demonstrated a statistically significant increase in tumor tissue samples (p < 0.05). Noteworthy, statistical analysis revealed a significant relationship between Enterococcus and prior cancer (p < 0.05). Conclusions: These findings provide significant insight into the complex association between the gut microbiota and CRC and may pave the way for future research on novel screening methods, preventive measures, and therapeutic strategies targeting the gut microbiota in CRC patients.