Distinguishing the significance of blood microbes in epithelial ovarian cancer

The human microbiome has generated growing interest in epithelial ovarian cancer (EOC) research, yet investigations of the blood microbiome remain sparse. This study explored plasma microbial signatures unique to EOC. We accessed 180 age/race/ethnicity-matched archival plasma samples from women with (1) EOC; (2) commonly diagnosed non-EOC solid tumors in women; (3) benign gynecologic conditions; and (4) age/race/ethnicity-matched controls. The microbial profiles of the plasma specimens were assessed using an amplicon-based sequencing method that targets the 16S rRNA gene in the bacterial genome. A stringent bioinformatic pipeline was applied to filter out suspicious bacterial contaminants at the genus level. Bioinformatic decontamination analysis removed 225 high-risk bacterial contaminants. The remaining 339 high-confidence bacteria were included in the final analysis for differential abundances in the plasma between the study groups. Women with EOC, which were primarily of the high-grade serous ovarian carcinoma histologic subtype, had significantly distinct differential abundances of the genera Brevibacterium (p < 0.001), Chloronema (p < 0.001), Facklamia (p < 0.001), Sutterella (p < 0.001), and Zymomonas (p < 0.001) when compared to the other study groups. These results suggest that plasma EOC-associated bacteria could be further exploited in follow-up studies to validate clinical applicability in disease screening, diagnostics, and risk stratification.