Characterization of the Saliva Microbiome in Women with Suspicious Mammograms

Abstract

Breast cancer (BC) is the most common cancer type in women worldwide. Recent studies have shown significant differences among the microbiome composition in BC patients compared to healthy individuals and suggested breast microbiome may play an active role in BC emergence and progression. Also, dysbiotic microbiota outside the breast may correlate with BC status in patients. Currently, only 20 percent of women recalled after a positive mammogram for further examination are diagnosed with a malignant lesion, thus a complementary approach that could improve mammography specificity is needed. In this study, we aimed to describe the saliva microbiome in women with BC to lay the groundwork for a noninvasive biofluid test that can improve BC diagnosis while reducing its cost. We applied nanotechnology combined with high-resolution LC-MS/MS to sequester, concentrate, and detect protein biomarkers from the saliva of 20 women with suspicious mammograms, 10 of whom were BC patients and 10 were healthy. With PEAKS and HoneyMeter, we analyzed peptides, described our samples’ microbiome composition, and reviewed these species’ characteristics. We identified differentially expressed proteins in cases versus controls (absolute fold change > 1.5), along with peptides from cancer-related pathogens like F. nucleatum and P. gingivalis and from bacteria like B. subtilis, which might play a protective role. Future research will focus on investigation of these and other BC microbiome species and the validation of peptide markers with targeted MS.