Jemmie Hoang, Stephanie Gilbertson-White, Nicole Cady, Meeta Yadav, Shailesh Shahi, Leeann Aguilar, Ashutosh K. Mangalam, Catherine Cherwin

Alterations in the naturally occurring bacteria of the gut, known as the gastrointestinal (GI) microbiome, may influence GI symptoms in women with breast cancer. This work aims to describe GI symptom occurrence, duration, severity, and distress and measures of the GI microbiome among women with breast cancer receiving chemotherapy compared to age- and sex-matched healthy controls. 22 women with breast cancer receiving chemotherapy and 17 healthy control women provided stool specimens and GI symptom data using the modified Memorial Symptom Assessment Scale (MSAS). The fecal microbiome was profiled by metagenomic sequencing of 16S Ribosomal RNA (rRNA). GI microbiome was compared between groups using alpha-diversity (Observed OTU number and Shannon index), beta-diversity (UniFrac distances), and relative abundance of select genera. GI symptoms with high symptom reports among breast cancer patients included nausea, diarrhea, flatulence, dry mouth, taste change, and poor appetite. Indices of differential abundance (beta diversity) significantly distinguished between breast cancer patients and healthy controls. Unique bacterial features differentiating the 2 groups were Prevotella_9, Akkermansia, Lachnospira, Lachnospiraceae_NK4A136, Lachnoclostridium, and Oscillibacter. Gut bacteria are associated with GI inflammation and mucus degradation, suggesting the potential role of the GI microbiome in GI symptom burden. Understanding the influence of GI bacteria on gut health and symptoms will help harness the enormous potential of the GI microbiome as a future diagnostic and therapeutic agent to reduce the symptom burden associated with chemotherapy.