Breast tissue, oral and urinary microbiomes in breast cancer Original paper

What was studied?

This study aimed to explore the role of the microbiome in breast cancer, specifically comparing the microbiomes of breast tissue, oral cavity, and urinary tract in women with and without breast cancer. The researchers hypothesized that cancerous breast tissue would have a distinct microbiome compared to benign tissue and that microbiomes from distant sites (oral and urinary) would also show signs of dysbiosis. The microbial profiles were analyzed by amplifying the bacterial 16S rRNA gene from various samples and analyzing them with QIIME-based bioinformatics tools.

Who was studied?

The study enrolled 78 women, including 57 women with invasive breast cancer undergoing mastectomy and 21 healthy women undergoing cosmetic breast surgeries such as mammoplasty or mastopexy. The participants were stratified by their cancer status, menopausal status, and other clinical characteristics, including body mass index (BMI) and age. Samples from breast tissue, oral rinse, and urine were collected for analysis.

Most important findings

The study revealed significant differences in the microbiomes of breast tissue from cancer patients compared to non-cancer controls. Notably, cancer patient breast tissue exhibited decreased relative abundance of Methylobacterium, a finding linked to breast cancer pathology. However, there were no significant differences in oral microbiomes between cancer and non-cancer patients. Urinary microbiomes, on the other hand, showed differences largely explained by menopausal status, with peri/postmenopausal women having decreased levels of Lactobacillus. Cancer patients, independent of menopausal status, showed increased levels of gram-positive bacteria, including Corynebacterium, Staphylococcus, Actinomyces, and Propionibacteriaceae, suggesting a distinct microbiomic pattern in cancer patients, particularly in the urinary microbiome.

Key implications

The findings highlight the potential for using microbiome analysis as a tool for understanding breast cancer, suggesting that the microbiomes of different body sites, particularly the breast tissue and urinary microbiomes, may serve as biomarkers for cancer. Specifically, the altered microbial profile in cancerous breast tissue, alongside the observed dysbiosis in urinary microbiomes, could provide insight into how systemic factors, such as hormonal changes, affect microbial communities in cancer patients. Further investigation is needed to validate these associations in larger cohorts and to explore potential therapeutic implications.