A prospective randomized controlled study of the effects of probiotics on intestinal microecology and gastrointestinal side effects in patients undergoing postoperative chemotherapy for breast cancer

Background Breast cancer poses a serious threat to women's health, and chemotherapy is a classic treatment for it. However, chemotherapy-induced gastrointestinal toxicity can lead to disease aggravation, treatment failure and even death. Bifico is a commonly used probiotic. This study aimed to explore the effects of Bifico on gastrointestinal side effects caused by chemotherapy. Methods A total of 50 breast cancer patients were enrolled and randomly divided into a treatment group (TG) and a control group (CG) using a 1:1 randomization method. Blood and stool samples were collected and analyzed before the first and third chemotherapy treatment course. The fecal microbiota was analyzed through 16S ribosomal RNA sequencing. The level of serum zonulin was detected before and after chemotherapy. Results After two cycles, the TG showed a richer gut microbiota with increased beneficial bacteria and reduced pathogenic bacteria compared to the CG. Functional analysis indicated the TG's microbiota was involved in polyamine synthesis, while the CG's microbiota was linked to teichoic acid production. Serum zonulin levels decreased significantly in the TG, reflecting improved intestinal barrier function. The TG also had fewer gastrointestinal side effects, particularly constipation and oral mucositis. Additionally, the TG exhibited higher IgG levels and lower triglyceride and small dense low-density lipoprotein levels. Immune function was enhanced in the TG, with increased total T cells, Th cells, and B cells. Conclusion This study revealed that Bifico can maintain intestinal barrier function, reducing chemotherapy-induced gastrointestinal side effects, and modulate gut microbiota in breast cancer patients.