Gut Microbiota composition after diet and probiotics in overweight breast cancer survivors: a randomized open-label pilot intervention trial

•Breast cancer is the most common cancer in women worldwide, and lifestyle and diet could be affected along with appearance.•Obesity and intestinal microbiota composition may be associated with breast cancer and with a distortion of the microbial homeostasis and reduced bacterial biodiversity.•Overweight and obesity are associated with advanced stage and grade of cancer at diagnosis and resistance to local and systemic therapies.•Dietary supplementation with probiotics, such as bacterial strains exerting beneficial effects on their host, regulates the gut microbiota structure and function through the interaction with the commensal bacteria and the expression of microbial enzymes.