About one in eight women in the United States (12%) will develop invasive breast cancer over the course of her lifetime. It is by far the commonest cancer in women in the United States, accounting for approximately 30% of all cases in women. Breast cancer death rates are higher than those for any other cancer, besides lung cancer. e situation is similar in Northern Europe, while other EU countries (like Spain and Greece) have much lower incidence, although mortality rates are still comparable (Ferlay et al. 2010a, b). Less industrialized countries, like parts of Asia and Africa, are generally less aected, but the risk for women who migrate from low-to high-risk countries typically increases, suggesting a strong eect for lifestyle or environmental factors (Deapen et al. 2002).