The Impact of Obesity on Breast Cancer

The rates of obesity are increasing worldwide and this condition is now recognized as a leading preventable cause of cancer. Several diseases are directly related to obesity, including diabetes, hypertension, atherosclerosis, stroke, musculoskeletal disorders, and a diverse range of malignances—such as breast cancer. Obesity is associated with an increased risk of postmenopausal estrogen receptor-positive breast cancer and worse cancer-related outcomes for all breast tumor subtypes. Several mechanisms have been proposed to contribute to the obesity-cancer link, including high levels of circulating and local estrogens, altered amounts of adipokines (leptin and adiponectin), disrupted insulin/IGF signaling, modifications within the microbiome, and local and systemic effects of inflammation. Here we will review recent advances in our understanding of the complex signaling pathways underlying the obesity-cancer link. An improved understanding of these processes is anticipated to propel novel and effective intervention strategies to reduce the global obesity-cancer burden.