2ⁿᵈ Edition of the Cancer R&D World Conference 2026

Abstract

Breast cancer is the second leading cause of cancer death in women. New approaches for early detection and individual assessment of modifiable risk factors are needed to reduce breast cancer-associated deaths. Aberrant DNA methylation of breast tissue is a feature of all breast cancers and occurs years to decades before cancer is detected, potentially providing both accurate risk assessment and early detection. Importantly, DNA methylation is reversible with diet and drugs, representing a truly modifiable risk factor. However, assessment of DNA methylation requires breast tissue. Human milk contains sloughed epithelial cells originating throughout the mammary gland. Here, we present proof of principle for human milk as a liquid biopsy. I focused on BRCA mutation carriers as their risk of cancer is extremely high and currently many women with pathogenic germline BRCA mutations choose to have a bilateral risk-reducing mastectomy, though not all will develop breast cancer. Comparison of genome-wide DNA methylation in bilateral milk samples collected from healthy BRCA mutation carriers and those who developed breast cancer reveals a methylation-risk profile detectable in milk. Given that 84% of women give birth and produce milk, results from this study have broad applications for accurate risk assessment and cancer prevention.