Obesity and Breast Cancer: A Complex Relationship.

As prevalence of obesity continues to rise in the United States, we are beginning to elucidate the complex role of obesity-associated chronic inflammation, endocrine dysfunction, and hormone production as a driver for increased breast cancer risk. Epidemiological data suggest that obesity (BMI > 30) is associated with increased breast cancer incidence, worse prognosis, and higher mortality rates. Mechanistically, obesity and excess fat mass represent a state of chronic inflammation, insulin resistance, adipokine imbalance, and increased estrogen signaling. This pro-tumorigenic environment stimulates cancer development through abnormal growth, proliferation, and survival of mammary tissue. Importantly, obesity is a modifiable risk factor; alterations in cell proliferation, apoptosis, circulating estrogen, and insulin sensitivity are observed in response to weight loss attainable through behavior modification including dietary and exercise changes.