Abstract
The use of faecal microbial markers as non-invasive biomarkers for colorectal cancer (CRC) has been suggested, but not fully elucidated. Here, we have evaluated the importance of Parvimonas micra as a potential non-invasive faecal biomarker in CRC and its relation to other microbial biomarkers. The levels of P. micra, F. nucleatum and clbA + bacteria were quantified using qPCR in faecal samples from a population-based cohort of patients undergoing colonoscopy due to symptoms from the large bowel. The study included 38 CRC patients, 128 patients with dysplasia and 63 controls. The results were validated in a second consecutive CRC cohort including faecal samples from 238 CRC patients and 94 controls. We found significantly higher levels of P. micra in faecal samples from CRC patients compared to controls. A test for P. micra could detect CRC with a specificity of 87.3% and a sensitivity of 60.5%. In addition, we found that combining P. micra with other microbial markers, could further enhance test sensitivity. Our findings support the potential use of P. micra as a non-invasive biomarker for CRC. Together with other microbial faecal markers, P. micra may identify patients with “high risk” microbial patterns, indicating increased risk and incidence of cancer.
Highlights
The use of faecal microbial markers as non-invasive biomarkers for colorectal cancer (CRC) has been suggested, but not fully elucidated
The level of P. micra was analysed in faecal samples from 38 cancer patients, 128 patients with dysplasia, and 63 matched controls from the Faecal and Endoscopic Colorectal Study in Umeå (FECSU) cohort, which is a population-based cohort of patients undergoing colonoscopy due to large bowel symptoms
P. micra was significantly more abundant in faecal samples from CRC patients compared to controls in the FECSU cohort (P < 0.001; Fig. 1A)
Summary
The use of faecal microbial markers as non-invasive biomarkers for colorectal cancer (CRC) has been suggested, but not fully elucidated. We have evaluated the importance of Parvimonas micra as a potential non-invasive faecal biomarker in CRC and its relation to other microbial biomarkers. The levels of P. micra, F. nucleatum and clbA + bacteria were quantified using qPCR in faecal samples from a population-based cohort of patients undergoing colonoscopy due to symptoms from the large bowel. A microbial driver-passenger model for carcinogenesis has been suggested, where some bacteria promote cancer while others accumulate due to higher fitness in the resulting altered microenvironment[13]. The role of P. micra in CRC progression is still largely unknown, and the potential of P. micra as a faecal marker for CRC detection has not been fully elucidated
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