Microbiome Patterns Vary Among Individuals with Different Cancer Types and Onset Age

Researchers from the Mayo Clinic have found that the gut microbiome varies significantly among adults with different types of cancer who were diagnosed at various ages. The study analyzed stool samples from 1,364 cancer patients in the Mayo Clinic Cancer Microbiome cohort, which included patients from Arizona, Florida, and Minnesota. The researchers compared the cancer patients with 287 non-cancer individuals to identify broad differences in the gut microbiome.

The analysis revealed that neuroendocrine tumors had a reduced presence of common gut bacteria, while liver and intrahepatic bile duct cancers showed higher levels of specific bacteria, including Enterococcus faecalis. Esophageal cancer exhibited higher levels of six bacterial species, including Streptococcus. In lymphoid leukemia and multiple myeloma, distinct links were also identified.

Among younger patients, those with colorectal cancer had higher lactate levels and more Veillonella parvula, a bacterium that feeds on lactate produced by tumors. Younger patients with breast cancer had lower levels of primary bile acids and changes in 64 bacterial species. Clostridium scindens, a bacterium involved in bile acid and steroid metabolism, was found to be different in younger breast cancer patients.

The study also identified gut bacteria associated with survival in various cancer types. In liver and intrahepatic bile duct cancer, Bifidobacterium longum was linked to longer survival, while Blautia A massiliensis was associated with shorter survival. The researchers found that before treatment, patients receiving 5-fluorouracil, a chemotherapy drug used for many cancers, had lower levels of bacterial genes that break down the drug.

Those who later developed diarrhea had fewer of these genes, which were mostly from Anaerostipes hadrus, a common gut bacterium.

The findings suggest that the gut microbiome may play a role in cancer development and treatment outcomes, but further research is needed to determine if these microbial changes cause early-onset disease. The researchers plan to investigate whether cancer-specific microbial signals play a causal role in disease and to validate the microbiome's potential to predict treatment side effects in larger patient groups.