Estrogen Dominance & Thermography: What Your Breasts are Trying to Tell You Lifetime exposure to estrogen has been identified as a significant risk factor for the development of cancer. More and more today, women and their health care providers are choosing to monitor hormonal levels. When we measure the level of estrogen and progesterone in the blood, urine, or saliva we are looking at the hormonal balance in the whole body. These are all useful tools providing useful infor