Lester, Sara P.

Abstract In screening for breast cancer (BC), mammographic breast density (MBD) is a powerful risk factor that increases breast carcinogenesis and synergistically reduces the sensitivity of mammography. It also reduces specificity of lesion identification, leading to recalls, additional testing, and delayed and later-stage diagnoses, which result in increased health care costs. These findings provide the foundation for dense breast notification laws and lead to the increase in patient and provider interest in MBD. However, unlike other risk factors for BC, MBD is dynamic through a woman’s lifetime and is modifiable. Although MBD is known to change as a result of factors such as reproductive history and hormonal status, few conclusions have been reached for lifestyle factors such as alcohol, diet, physical activity, smoking, body mass index (BMI), and some commonly used medications. Our review examines the emerging evidence for the association of modifiable factors on MBD and the influence of MBD on BC risk. There are clear associations between alcohol use and menopausal hormone therapy and increased MBD. Physical activity and the Mediterranean diet lower the risk of BC without significant effect on MBD. Although high BMI and smoking are known risk factors for BC, they have been found to decrease MBD. The influence of several other factors, including caffeine intake, nonhormonal medications, and vitamins, on MBD is unclear. We recommend counseling patients on these modifiable risk factors and using this knowledge to help with informed decision making for tailored BC prevention strategies.

Menopausal hormone therapy (HT) aims to improve a woman's quality of life by treating bothersome menopausal symptoms associated with low estrogen levels. Although HT is prescribed to millions of women worldwide, its breast-related adverse effects have always been a concern. Some of the common adverse effects of HT are breast fullness, increased breast density, and increased breast cancer (BC) risk. Health care professionals need to be aware of the influence of HT on breast tissue to provide appropriate counseling as part of informed decision making. Our review summarizes the influence of HT on breast symptoms, breast density, mammograms, and BC risk.