biostudies-literatureUnknown9(11)McCune EBreast Cancer Research Foundation (BCRF)Breast Cancer Research FoundationCalifornia Breast Cancer Research ProgramCalifornia Breast Cancer Research Program (CBCRP)This study characterized and compared the fecal and oral microbiota from women with early-stage breast cancer (BC), women with ductal carcinoma <i>in situ</i> (DCIS), and healthy women. Fecal and oral samples were collected from newly diagnosed patients prior to any therapy and characterized using 16S rRNA sequencing. Measures of gut microbial alpha diversity were significantly lower in the BC vs healthy cohort. Beta diversity differed significantly between the BC or DCIS and healthy groups, and several differentially abundant taxa were identified. Clustering (non-negative matrix factorization) of the gut microbiota identified five bacterial guilds dominated by <i>Prevotella</i>, Enterobacteriaceae, <i>Akkermansia</i>, Clostridiales, or <i>Bacteroides</i>. The <i>Bacteroides</i> and EnteromSystemse0123724https://www.ebi.ac.uk/biostudies/studies/S-EPMC11575313biostudies-literatureGut and oral microbial compositional differences in women with breast cancer, women with ductal carcinoma &lt;i&gt;in situ&lt;/i&gt;, and healthy women.PMC11575313Heditsian DSharma AO'Meara TBrain SMcCune ETheiner SEsserman LJohnson BCampos MCampbell MJGilbert JAfalseGut and oral microbial compositional differences in women with breast cancer, women with ductal carcinoma &lt;i&gt;in situ&lt;/i&gt;, and healthy women.This study characterized and compared the fecal and oral microbiota from women with early-stage breast cancer (BC), women with ductal carcinoma <i>in situ</i> (DCIS), and healthy women. Fecal and oral samples were collected from newly diagnosed patients prior to any therapy and characterized using 16S rRNA sequencing. Measures of gut microbial alpha diversity were significantly lower in the BC vs healthy cohort. Beta diversity differed significantly between the BC or DCIS and healthy groups, and several differentially abundant taxa were identified. Clustering (non-negative matrix factorization) of the gut microbiota identified five bacterial guilds dominated by <i>Prevotella</i>, Enterobacteriaceae, <i>Akkermansia</i>, Clostridiales, or <i>Bacteroides</i>. The <i>Bacteroides</i> and Entero2024-01-01T00:00:00Z2024 Nov2025-04-04T20:38:47.882Z2025-04-04T20:38:47.882ZS-EPMC115753133947018910.1128/msystems.01237-24