Microbial dysbiosis is the cause of colorectal cancer onset

Purpose: An increasing amount of evidence suggests a role for microbiota in colorectal cancer (CRC). If supposed that microbial dysbiosis is the cause of CRC, it might be possible to prevent CRC by improving the intestinal environment. We investigated the changes of intestinal environments in each stage of CRC and adenoma.
Methods: We analyzed 13 groups of microbiota, 8 types of organic acids, and pH in feces of the following 3 groups: 93 patients with CRC, 22 with adenoma, and 27 without adenoma.
Results: Five groups of obligate anaerobe and 2 groups of facultative anaerobes were significantly lower in the CRC group than in the healthy individuals. While the concentrations of short chain fatty acids (SCFAs) were significantly decreased in the CRC group, pH was increased in the CRC group. Comparison among the CRC, adenoma, and non-adenoma groups revealed that SCFAs and pH in the adenoma group were intermediate to the CRC group and the non-adenoma group. No differences in microbiota were observed among Dukes stages.
Conclusions: CRC patients showed significant differences in the intestinal environment, including alterations of microbiota, decreased SCFAs, and elevated pH. These changes are not a result of CRC progression but are involved in CRC onset. Our results indicate that CRC can be prevented by stabilizing intestinal environment.