Table 1.

Published studies of circulating bacterial DNA in cancer.

Cancer type	Methodology	Main findings	Study
Breast	Metagenomics analysis of plasma DNA	cbDNA identified as a potential prognostic indicator	Huang et al. (16)
Gastric	16S rRNA sequencing of serum samples	Lower alpha diversity in cancer patients compared to controls; specific taxa correlate with clinical indices	Dong et al. (17)
Hepatocellular	16S rRNA sequencing of serum samples	Lower alpha diversity in cancer patients compared to controls; Differentially abundant taxa between cancer and controls; Development of 5-microbial gene marker panel	Cho et al. (18)
Ovarian	Metagenomic analysis of bacterial DNA derived from extra-cellular vesicles from serum samples	Different metagenomic profiles between cancer and controls. Acinetobacter common to cancer samples	Kim et al. (19)
Colorectal	Metagenomics analysis of plasma DNA	Slightly lower diversity in cancer samples; cbDNA mainly from gut-associated species; 28-species model could distinguish cancer from controls.	Xiao et al. (21)
	PCR amplification of specific microbial targets (16S gene, E. coli, B. fragilis, C. albicans) from whole blood samples	Higher detection of all fragments, except E. coli, in cancer samples; detection of microbial fragments associated with metastasis	Messaritakis et al. (22)
	PCR amplification of specific microbial targets (16S gene, E. coli, B. fragilis, C. albicans) from whole blood samples	Association between detection of microbial fragments and circulating tumor cells	Koulouridi et al. (23)
Multiple cancer types	Whole genome sequencing of whole blood samples; metagenomic analysis of plasma samples	Circulating microbial DNA profiles can distinguish between multiple types of cancer, including low-grade tumors; similar discrimination seen in plasma analysis	Poore et al. (24)