Oral Bacteria Linked to Breast Cancer

A Johns Hopkins–led study (published in Cell Communication and Signaling) found that the oral bacterium Fusobacterium nucleatum can bind to, enter, and persist in breast cells in mouse models and human cell lines, causing DNA damage, inflammation, and increased expression of proteins tied to invasion and chemotherapy resistance. Cells carrying BRCA1 mutations were especially susceptible because they overexpress a sugar that the bacterium uses to attach and enter, suggesting a gene–environment interaction. — If replicated in humans, this changes prevention and screening priorities by making oral health and microbial surveillance a potential component of cancer risk reduction and by highlighting infections as modifiable cofactors for genetically susceptible people.