Objective: The aim of this study was to investigate the relationship between gut microbiota and breast cancer by analyzing cancerous breast tissue, normal breast tissue, and stool samples from patients diagnosed with breast cancer who underwent breast-conserving surgery.
Materials and Methods: Stool samples and per-operative cancerous and non-cancerous breast tissue samples were collected from patients diagnosed with breast cancer who were scheduled for breast-conserving surgery and met the specified criteria. Data on patients’ age, height, weight, body mass index (BMI), history of additional diseases, allergy history, menopausal status, menstrual regularity, breastfeeding history, oral contraceptive use, previous surgeries, family history of breast cancer, recent antibiotic use, COVID-19 infection and vaccination history, histological subtype and stage of breast cancer, malignant/normal breast tissue samples, and stool samples were collected and analyzed by using 16S rRNA amplicon sequencing.
Results: The study included 22 female patients diagnosed with stage 1-2 breast cancer between 2022-2023 in a single center. The average age of the patients was 58.30±12.73 years, and mean BMI was 28.85±3.13 kg/m2. However, only 7 (31.8%) had a BMI below 30, and 15 patients (68.2%) had a BMI above 30. No significant differences were found between demographic and clinical characteristics and microbiota composition of the individual patients. Microbiota analysis revealed significant differences in the growth patterns of various genera, families, and species of bacteria in tumor and normal breast tissue samples. In particular, it was found that the genera Ruminococcus, Eubacterium, Actinobacter, and Stenotrophomonas were increased in tumor tissue compared to normal breast tissue, while the genera Lactobacillus, Staphylococcus, Bifidobacterium, Propionibacterium, Lactococcus, Proteobacteria, Burkholderia, Faecalibacterium, and Pelomonas were more abundant in normal breast tissue compared to tumor tissue.
Conclusion: Despite the small sample size and some limitations of the methods used in microbiota analysis., different growth patterns of bacterial genera, families, and species were identified in cancerous and non-cancerous breast tissue. Future studies with larger and more diverse populations will contribute to a better understanding of the relationship between microbiota and breast cancer.