More precancerous lesions found after fecal sampling
There were more cases of precancerous lesions found after fecal sampling, reported Dr. Gacesa.
Before fecal sampling, 219 participants had colonic lesions, including low-grade dysplasia, high-grade dysplasia, and serrated polyps, and 26 cases of CRC. A total of 315 participants developed assorted colonic lesions after fecal sampling, with a total of 29 cases of CRC.
When the researchers looked at microbiome diversity in people who had experienced precancerous colonic lesions 1-5 years before fecal sampling, they found that diversity was lower, compared with controls. Microbiome diversity was also decreased in participants who developed colonic lesions after sampling.
The microbiome composition and function were different between patients with preexisting and future lesions, and varied based on the types of lesion.
“We saw a drop in some commensal bacteria, including Faecalibacterium, in both those with recent pathologies and those who developed them in the future. We also saw a massive spike in Alistipes finegoldii in those who had CRC, strongly suggesting it is closely linked to CRC in people,” reported Dr. Gacesa.
Among bacterial species linked with the future development of precancerous lesions were those from the family of Lachnospiraceae, and the genera Roseburia and Eubacterium. Microbiome composition had a moderate predictive power for future lesions and CRC.
“Precancerous lesions are linked to the gut microbiome,” Dr. Gacesa said. “Adenomas – both preexisting ones (before fecal sampling), and ones that came after fecal sampling – are significantly linked to the microbiome composition.”
More time needed
Loris Lopetuso, MD, gastroenterologist, from Fondazione Policlinico Universitario Agostino Gemelli, Rome, who comoderated the session, remarked that the data were intriguing and important.
“We really need to find new predictors of tumorigenesis,” he said. “We already have some good predictors, mainly FIT, but these are not enough. These gut microbiota look promising.”
He added that the study by Dr. Gacesa’s team was one of the largest he had seen. “But I would note that, methodologically, we need to remember that the time between a fecal sample and the development of polyps can be very large,” Dr. Lopetuso emphasized. “This study looked at around 5 years only. Also, the microbiota can change from one day to the other in response to stress, diet, and many other things.”
However, “this could be the beginning of a longitudinal study between cases and controls because many years are needed,” he added.
Dr. Gacesa has received funding from Janssen Pharmaceuticals for an unrelated research project. He is a paid R&D consultant for Esox Biologics Ltd for topics unrelated to this project. Dr. Lopetuso reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.