COPENHAGEN – according to a large, 22-year analysis from the Dutch Microbiome Project cohort study.
The findings suggest a possible role for gut microbiota in the development of colorectal lesions and cancer, said study lead Ranko Gacesa, PhD, from the department of gastroenterology, University of Groningen (the Netherlands), who presented the results at the annual United European Gastroenterology Week.
“It [also] suggests that gut bacteria might enhance currently used noninvasive fecal tests for the detection of colorectal polyps, and even that microbiome-modulating therapies might play a role in prevention of colorectal cancer,” said Dr. Gacesa, who won the award for best abstract in the meeting session.
The gut microbiome is known to be linked to colorectal cancer (CRC); in particular, the bacteria Bacteroides fragilis and Alistipes finegoldii have been found to cause CRC in mouse models, explained Dr. Gacesa.
In the current study, Dr. Gacesa and colleagues looked at the potential for the gut microbiome in humans to play a role in the detection of precancerous colonic lesions. The noninvasive fecal immunochemical test (FIT), recently shown to be a preference among patients, produces a high number of false-positive results, leading to many unnecessary colonoscopies.
“It has been calculated that the use of a fecal microbiota analysis combined with FIT in the early-stage prediction of CRC could result in a high true-positive rate and a low false-positive rate,” said Dr. Gacesa. “In this way, we might reduce the false-positive rate by around 50%.
“Ideally, we don’t want to detect cancer when it is already established and is hard to treat. We want to detect it as early in its development as possible,” he said.
Longitudinal analysis using large Dutch databases
To determine the direction of the relationship between CRC and the gut microbiome, the Dutch researchers conducted a longitudinal analysis from 2000 to 2022, looking at whether CRC alters the gut microbiome, as well as whether changes in the microbiome contribute to the development of precancerous lesions and CRC.
They drew on data from the Dutch colorectal cancer screening program, comprising FIT results in people aged 55 years and older, and colonoscopy if referred. They recorded cases of colonic biopsies from the extensive Dutch national database of medical biopsies. These were then linked with Dutch microbiome project data sourced from fecal samples of 8208 individuals taken between 2012 and 2015.
“This allowed us to associate gut microbiome compositions and functions to detailed histological information about precancerous lesions and CRC, including when lesions were detected relative to fecal sampling [and a reading of the gut microbiome],” Dr. Gacesa explained.
The analysis determined the composition, function, and genomic profiles of gut microbiota in participants who developed precancerous colorectal lesions before fecal sampling from 2000 to 2015, and in those participants who developed lesions after fecal sampling, between 2015 and 2022. Clinical phenotypes, comprising the type and size of lesions, were noted. The control group included 2123 individuals from the general population with normal colonoscopy findings.