Cancer
Colorectal cancer risk linked to gut microbiome alterations
For immediate release: May 27, 2026
Boston, MA—More than a decade after removal of an adenoma—a precancerous mass—from the colon, alterations to the gut microbiome and metabolites remain and may drive heightened risk of colorectal cancer (CRC), according to a new study led by researchers at Harvard T.H. Chan School of Public Health. The study also found that diet and physical activity were more closely tied to the abundance of these CRC-associated gut microbes in people with a history of adenoma than in adenoma-free individuals, suggesting lifestyle may play a particularly important role in shaping these microbes in this high-risk group.
CRC is the second leading cause of cancer-related death worldwide, and adenoma removal is one of the most effective prevention tools. Yet people who’ve had this procedure still face an elevated risk of CRC. The biological reasons why have remained unclear, but the gut microbiome—the collection of trillions of bacteria living in the gastrointestinal tract—is a plausible suspect
“Our study was the first to address whether gut microbial and metabolic alterations are still detectable many years after adenoma removal,” said corresponding author Mingyang Song, associate professor of clinical epidemiology and nutrition. “The answer is yes—suggesting that removing an adenoma doesn’t return the gut to a low-risk state, and that the gut microbiome may therefore be a significant biological contributor to sustained CRC risk.”
The study was published May 27 in Cell Host & Microbe
Previous research linking the gut microbiome to CRC risk examined patients’ gut microbiomes only around the time of adenoma removal. For this study, the researchers took a long-term approach using health data and stool samples from women enrolled in the Nurses’ Health Study II. They studied the microbiomes of 354 participants who had an adenoma removed from their colon and compared them to the microbiomes of 354 adenoma-free participants closely matched in age and background. Stool samples were collected on average 12 years after adenoma removal.
The study found that significant differences persisted between the gut microbiomes and metabolites of adenoma-free participants and those who’d had an adenoma, even more than a decade after removal. The latter group had microbiomes that partially resembled those belonging to CRC patients. Among participants with a history of adenoma, those with less healthy diets and lower physical activity carried more of the microbes that are typically elevated in both adenoma and CRC patients. These links between lifestyle and microbes were tighter in participants with a history of adenoma than in adenoma-free participants.
“The fact that CRC-associated gut microbial and metabolic features are still detectable a decade later suggests the gut microbiome may be part of sustained CRC risk,” said first author Ana Nogal, postdoctoral research fellow in the Department of Epidemiology. “Diet and lifestyle were closely tied to these microbes, raising the possibility that these habits could influence the gut environment in people at higher risk.”
The researchers noted that the study shows association rather than causation, and that future research is needed to directly test whether modifying the gut microbiome through diet and exercise habits does successfully alter CRC risk
“Long-lasting gut microbiome and fecal metabolome alterations after colorectal adenoma removal and their relationship to colorectal cancer,” Ana Nogal, Kai Wang, Kelsey N. Thompson, Hanseul Kim, Amrisha Bhosle, Gianmarco Piccinno, Sagun Maharjan, Chahat Upreti, Long H. Nguyen, Nicola Segata, Eric B. Rimm, Wendy S. Garrett, Andrew T. Chan, Curtis Huttenhower, Mingyang Song, Cell Host & Microbe, May 27, 2026, doi: 10.1016/j.chom.2026.05.001
This work was supported by the National Institutes of Health (UM1 CA186107, P01 CA87969, U01 CA176726, U01 HL145386; R35 CA253185, R01CA243454, U01CA261961, R01CA263776, and R00CA283146); team OPTIMISTICC; Prescient Metabiomics; the Cancer Research UK Grand Challenge Award (C10674 / A27140); and the American Cancer Society (MRSG-17-220-01 – NEC)
Segata is a founder and shareholder of PreBiomics Srl and is on the scientific advisory board of ZOE Ltd and received consultancy fees from them. Garrett has received research funding from Merck Sharp & Dohme, and Astellas Pharmaceuticals, and serves on the scientific advisory boards of Empress Therapeutics, Freya Biosciences, Sail Biosciences, and Seres Therapeutics. Huttenhower serves on the scientific advisory committee for Seres Therapeutics and Empress Therapeutics.
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For more information:
Maya Brownsteinmbrownstein@hsph.harvard.edu
Harvard T.H. Chan School of Public Health is a community of innovative scientists, practitioners, educators, and students dedicated to improving health and advancing equity so all people can thrive. We research the many factors influencing health and collaborate widely to translate those insights into policies, programs, and practices that prevent disease and promote well-being for people around the world. We also educate thousands of public health leaders a year through our degree programs, postdoctoral training, fellowships, and continuing education courses. Founded in 1913 as America’s first professional training program in public health, the School continues to have an extraordinary impact in fields ranging from infectious disease to environmental justice to health systems and beyond.
Cancer,Food, Nutrition, Diet,Preventative Care
Mingyang Song
Associate Professor of Clinical Epidemiology and Nutrition
Ana Nogal
Postdoctoral Research Fellow
