Altered microbiomes in breast tissue, urine of breast cancer patients
Breast cancer patients have notably different microbiomes in the local breast tissue and urinary tract, a recent study reveals. Particularly, species in the Methylobacterium genus are reduced in the local breast tissue while the urinary tract is enriched in gram-positive bacteria.
The study included 57 invasive breast cancer patients (mean age 55±14 years) who underwent mastectomy and 21 noncancer controls (mean age 43±14 years) who received cosmetic procedures. Taxa abundance was determined through sequencing of the 16s rRNA gene and subsequent bioinformatic analysis.
Compared to noncancer patients, the abundance of the genus Methylobacterium was significantly lower (p=0.03) and the relative abundance of an unknown genus of family Alcaligenaceae was significantly higher in tumour tissue from cancer patients (p=0.01).
In breast cancer patients, genus Methylobacterium was also relatively more abundant in normal tissue than in malignant tissue, but the difference did not reach significance.
Microbial diversity was also significantly higher in breast cancer patients who were hormone receptor-positive than in those who were not (p=0.03).
For the urine microbiome analysis, investigators used samples from 46 cancer patients and 19 noncancer participants, which showed comparable total number of 16s rRNA gene reads (p=0.15).
After controlling for menopausal status, significantly higher levels of the gram-positive bacteria Corynebacterium, Actinomyces and Staphylococcus were observed in breast cancer patients than in noncancer participants.
Bacterial diversity was also significantly greater in the urine samples collected from cancer patients than in noncancer participants.