LINE-1 methylation mediates the inverse association between body mass index and breast cancer risk: A pilot study in the Lebanese population

•Breast cancer is the most common cancer among women particularly in the Lebanese population, surpassing world averages.•BMI was inversely associated with premenopausal breast cancer risk, in line with World Cancer Research Fund (WCRF) reports.•LINE-1 methylation was higher in peripheral blood of breast cancer patients when compared to cancer-free women.•LINE-1 methylation mediates the inverse association between BMI and breast cancer risk.