Tumor-related bacteria may provide clues into early-onset colorectal cancer
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Researchers at Cleveland Clinic identified differences in tumor-related bacteria that may improve understanding of young-onset colorectal cancer.
The findings, published in eBioMedicine, could lead to new screenings or treatment approaches for this patient population.
Incidence of young-onset colorectal cancer — defined as cases among individuals aged younger than 50 years — has increased by 1.5% per year, according to American Cancer Society statistics.
“This research is the first step in exploring factors that could play a role in the rise of young onset colorectal cancer,” Shimoli V. Barot, MD, medical oncologist at Cleveland Clinic Cancer Institute, told Healio. “Having identified the tumor bacteria, we can now explore utilizing this information to devise strategies to address this challenge.”
Healio spoke with Barot about the findings and how this information could be used to improve treatment of and diagnostics for young-onset colorectal cancer.
Healio: What prompted you to conduct this study?
Barot: We are seeing increasing numbers of younger patients with colorectal cancer in our clinics. Studies have investigated the role of genetics, but we understand that a small number of these patients are genetically linked to young-onset colorectal cancer. Because disturbances in the microbiome have been linked to cancer, we hypothesized changes in lifestyle or environment may be affecting these bacteria and causing the rise in young-onset colorectal cancer.
Healio: How did you conduct this study?
Barot: We compared 136 patients aged younger than 50 years diagnosed with colorectal cancer with 140 patients diagnosed when they were aged older than 60 years. We obtained tumor samples and adjacent normal tissue from all patients. We did a 16S ribosomal RNA analysis, which studies the microbiome in the tumors, and evaluated if and how the bacteria differed between groups.
Healio: What did you find?
Barot: Bacteria involved in young-onset colorectal cancer tumors are very different than what we see in average-onset disease. The diversity of bacteria in younger patients was much higher, and younger patients had more left-sided and rectal tumors. Younger patients were more likely than average-onset colorectal cancer patients to have stage IV or metastatic disease. The two primary bacteria we recognized in younger individuals with colorectal cancer were Akkermansia and Bacteroides. The bacteria in the tumor also interacted with each other in a different way among the younger patients.
Healio: What are the potential implications of these findings?
Barot: Now that we know the primary bacteria associated with early-onset colorectal cancer, we can take the next step and investigate how they are acting, what they are producing, and how they are interacting with the immune system to lead to these changes. We can investigate whether these bacteria could be used as a detection marker to predict which patients are at increased risk for these cancers. Our findings also could have implications in terms of preventive treatments. For example, we could look into developing a probiotic or an antibiotic that would promote the good bacteria and kill the bad bacteria.
Our findings also could have implications in terms of treatments. Akkermansia has been linked to immunotherapy responses, so we could potentially exploit that among younger patients. It opens a lot of avenues, from preventions to diagnostics and therapeutics.
Healio: What is the next step in research?
Barot: We will need to compare the bacteria to that of individuals who don’t have colorectal cancer. Then we will try to figure out the role bacteria play in the pathogenesis of early-onset colorectal cancer. We want to determine what these bacteria are secreting, how they are interacting with the immune system around the tumor area, and how the immune system could be primed to fight these bacteria.
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For more information:
Shimoli V. Barot, MD, can be reached at Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; email: barots@ccf.org.
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