Fecal sample biobanking for breast cancer research focused on the gut microbiome.

Background: Gut microbiome is an emerging potentially modifiable contributor to breast health, including breast cancer (BCa). To advance prevention research in this area, we established a prospective biobanking cohort of cancer-free women. Methods: Eligible women were ≥40 years old, had no cancer history and no recent antibiotic use. Women were enrolled during screening mammography visits at three imaging centers in Florida (February 2021-June 2024), completed a BCa risk factor survey, and underwent body measurements. We collected digital mammograms and stool/urine/saliva samples. Optionally, women completed NIH's Diet History Questionnaire and a neighborhood stress questionnaire. Mammographic breast density (MBD) was assessed using established computerized approaches. Results: We recruited 733 cancer-free women (49% Caucasian, 21% African American, 26% Hispanic, and 4% from mixed/other races). The average age was 60 years (range 40-92); the majority (68.3%) were postmenopausal. BCa risk factor, neighborhood stress and diet questionnaires were completed by 97%, 65% and 58% of participants, respectively. Urine, saliva, and mammograms were available for all women; 83% also returned stool samples. Conclusions: We have established a representative cohort of screen-aged women with comprehensive BCa risk factor data, biospecimen collection, and MBD. Impact: This unique resource provides opportunity for future gut microbiome-focused BCa prevention research.