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One in 8 females in Canada are expected to develop breast cancer in their lifetime. (iStock)<\/p>\nOne in 8 females in Canada are expected to develop breast cancer in their lifetime. (iStock)<\/p>\n
A common oral bacterium associated with periodontal disease may drive the development and spread of breast cancer, particularly in genetically susceptible patients, according to new research from the Johns Hopkins Kimmel Cancer Center.<\/a><\/p>\n The study, published Jan. 15 in Cell Communication and Signaling, found that Fusobacterium nucleatum, a bacterium commonly found in the oral cavity, can travel through the bloodstream and colonize breast tissue, where it triggers DNA damage and other tumour-promoting changes.<\/p>\n Researchers reported that the bacterium accelerated tumour growth and increased metastasis to the lungs in preclinical models.<\/p>\n \u201cThe key takeaway is that this oral microbe can reside in breast tissue and that there is a connection between this pathogen and breast cancer,\u201d said Dipali Sharma, a professor of oncology and lead investigator.<\/p>\n Study builds on earlier oral-systemic health research<\/p>\n The Johns Hopkins team said its work was inspired by earlier studies that linked periodontal disease and breast cancer risk.<\/p>\n A prospective cohort study of 3,273 women, published in 2010, found that chronic periodontal disease \u2014 particularly when accompanied by tooth loss \u2014 was associated with a higher incidence of breast cancer over a 16-year follow-up period.<\/a><\/p>\n More recently, a 2025 systematic review examining studies published between 2000 and 2024 reported that periodontal disease may be associated with breast cancer development and progression, while emphasizing that a direct causal relationship has yet to be established.<\/a><\/p>\n Related: Harvard dental researchers explore AI for earlier head and neck cancer detection<\/a><\/p>\n Breast cancer in Canada<\/p>\n Breast cancer is the most common cancer among females living in Canada, excluding non-melanoma skin cancer. Public Health Agency of Canada says 1 in 8 females in Canada are expected to develop breast cancer in their lifetime<\/a>, and 1 in 36 are expected to die from it.<\/p>\n Ontario Health Study material has also noted that while diagnoses in older women have declined over the past 25 years, diagnoses among women under 50 have increased.<\/a><\/p>\n DNA damage and aggressive tumour behaviour<\/p>\n Using human breast cancer cells and mouse models, the new study found that exposure to F. nucleatum:<\/p>\n induced DNA damage and inflammatory responses<\/p>\n triggered abnormal cell growth and tissue changes<\/p>\n activated error-prone DNA repair pathways<\/p>\n increased tumour cell migration, invasion and chemotherapy resistance<\/p>\n The researchers also reported increased expression of DNA-PKcs, a protein linked to tumour progression and aggressive cancer behaviour.<\/p>\n