3.1. Introduction

Apart from skin cancer, breast cancer is the most common form of cancer affecting women in the U.S. It is also the most prevalent cancer affecting women of every ethnic group in the United States. Breast cancer currently affects more than one in ten women worldwide [3]. The rate of getting and dying from breast cancer differs among ethnic groups [4–6]. Recent studies showed that new cases of breast cancer are about the same for Black and White women. However, the incidence rate of breast cancer before age 45 is higher among Black women than White women, whereas between the ages of 60 and 84, breast cancer incidence rates are strikingly higher in White women than in Black women. Yet, Black women are more likely to die from breast cancer at every age [7, 8]. Meanwhile, incidence and death rates for breast cancer are lower among women of other racial and ethnic groups than among non-Hispanic White and Black women. Asian/Pacific Islander women have the lowest incidence and death rates [7, 8].

While racial and ethnic disparities in cancer survival remain, studies have identified potential reasons for this disparity and possible ways of reducing racial disparity in breast cancer outcome in our populations. Different subtypes of breast cancer have been identified; the ER+ and HER2/neu-positive subtype, the ER+ and HER2/neu-negative subtype, and the basal-like breast cancer also known as triple negative tumors which are high-grade tumors and the most aggressive subtype. The incidence of this subtype in Black women especially, younger ones is twice the incidence observed in White women. Studies have now shown that pregnancy and higher parity increase the risk of basal-like breast cancer but reduces the risk of ER+/PR+ breast cancer. However, breastfeeding was found to eliminate that increased risk of triple-negative cancer [9]. It is also observed that Black women have more children especially at a younger age and lower rate of breastfeeding than White women. These factors could account for the racial disparity in breast cancer. Other studies have identified possible differences in biological properties between Black women and White women, especially in the plasma levels of growth factors and hormones [10], reproductive factors [11, 12], susceptibility loci [13, 14], and primary tumor characteristics, including the presence and expression of steroid and growth factor receptors [12, 15–17], cell cycle proteins [18–20], tumor suppressor genes [21, 22], and chromosomal abnormalities [23]. These possible differences in biological properties between Black women and White women have the potential to influence breast cancer screening and treatment outcomes between the two ethnic groups. Since the early 1990s, several strategies, including early detection and diagnosis, reduction of tobacco smoking, widespread breast cancer screening, and improvement of breast cancer therapies, have been developed to improve the health of patients with breast cancer [24, 25].

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Despite medical improvements in early detection, diagnosis and screening, many Black women are less likely to obtain adequate treatment compared with White women [26, 27]. Given all the research work that has been conducted for breast cancer treatment with limited success for African Americans; new strategies and approaches are needed to promote breast cancer prevention, improve survival rates, reduce breast cancer mortality, and improve the health outcomes of racial/ethnic minorities. In addition, it is vital that leaders and medical professionals from minority population groups be represented in decision-making in research studies so that racial disparity in breast cancer can be well-studied, fully addressed, and ultimately eliminated in breast cancer.