ABSTRACT
Nutrition impacts cancer development and tumor progression through hormones and growth factors including insulin, insulin-like growth factors, cytokines, and reproductive hormones. Obesity and diet can lead to changes in the circulating levels of these substances that affect the multistep process of carcinogenesis at a cellular level. Obesity is accompanied by changes in estrogens formed in adipocytes and other tissues that can affect cancer risk. Reproductive steroids including estrogens and androgens have been implicated in multiple forms of cancer including breast cancer and prostate cancer. Insulin resistance associated with abdominal obesity, and elevated levels of insulin-like growth factor 1 can also increase cell proliferation in cancer cells. The effects of insulin on tumorigenesis are thought to be mediated by the insulin receptor, which is expressed in both normal tissues and tumors. Hyperinsulinemia stimulates mitosis in cells through well-known mediators and is increased in prediabetes, diabetes, and obesity. Gut and adipose hormones interact with the reproductive axis as well as with each other. There is increasing evidence that gut hormones and the microbiome interact in the complex interplay between nutrition, immune function, and inflammation relevant to cancer prevention, carcinogenesis, and tumor progression. This chapter reviews the evidence linking nutrition and hormones to cancer prevention, treatment, and relapse prevention.
