Dr Jun Wang and colleagues from Hong Kong evaluated the potential for diagnosing colorectal cancer from fecal metagenomes.
The research team performed metagenome-wide association studies on fecal samples from 74 patients with colorectal cancer and 54 controls from China, and validated the results in 16 patients and 24 controls from Denmark.
The researchers further validated the biomarkers in 2 published cohorts from France and Austria.
Finally, the team employed targeted quantitative PCR (qPCR) assays to evaluate diagnostic potential of selected biomarkers in an independent Chinese cohort of 47 patients and 109 controls.
Besides confirming known associations of Fusobacterium nucleatum and Peptostreptococcus stomatis with colorectal cancer, the team found significant associations with several species, including Parvimonas micra and Solobacterium moorei.
The research team identified 20 microbial gene markers that differentiated colorectal cancer and control microbiomes, and validated 4 markers in the Danish cohort.
In the French and Austrian cohorts, these 4 genes distinguished colorectal cancer metagenomes from controls with areas under the receiver-operating curve (AUC) of 0.72 and 0.77, respectively.
The team observed that qPCR measurements of 2 of these genes accurately classified patients with colorectal cancer in the independent Chinese cohort with AUC=0.84 and OR of 23.
These genes were enriched in early-stage patient microbiomes, highlighting the potential for using fecal metagenomic biomarkers for early diagnosis of colorectal cancer.
Dr Wang's team comments, "We present the first metagenomic profiling study of colorectal cancer fecal microbiomes to discover and validate microbial biomarkers in ethnically different cohorts, and to independently validate selected biomarkers using an affordable clinically relevant technology."
"Our study thus takes a step further towards affordable non-invasive early diagnostic biomarkers for colorectal cancer from fecal samples."