Potential of fecal microbiota for early-stage detection of colorectal cancer

Several bacterial species have been implicated in the development of colorectal carcinoma (CRC),but CRC-associated changes of fecal microbiota and their potential for cancer screening remain to beexplored. Here, we used metagenomic sequencing of fecal samples to identify taxonomic markers thatdistinguished CRC patients from tumor-free controls in a study population of 156 participants.Accuracy of metagenomic CRC detection was similar to the standard fecal occult blood test (FOBT) andwhen both approaches were combined, sensitivity improved > 45% relative to the FOBT,while maintaining its specificity. Accuracy of metagenomic CRC detection did not differsignificantly between early- and late-stage cancer and could be validated in independent patient andcontrol populations (N = 335) from different countries. CRC-associatedchanges in the fecal microbiome at least partially reflected microbial community composition at thetumor itself, indicating that observed gene pool differences may reveal tumor-relatedhost–microbe interactions. Indeed, we deduced a metabolic shift from fiber degradation incontrols to utilization of host carbohydrates and amino acids in CRC patients, accompanied by anincrease of lipopolysaccharide metabolism.