premenopausal obese women. Although evidence suggests that higher parity (having more children) reduces the risk of Luminal A breast cancer, recent studies found that higher parity also increased the risk of basal-like and ER− breast cancer.18, 19 Breast cancer subtypes differ in prevalence by age, with basal-like breast tumors more common among younger women.18 The different clinical, demographic, and risk factor profiles for breast cancer subtypes justify consideration of these subtypes as separate disease entities. Improved understanding of these subtypes is helping to explain some of the patterns of breast cancer and breast cancer disparities in population groups in the United States. This figure displays female breast cancer incidence rates in the United States for the years 1992 to 2009 for White, Black, American Indian and Alaska Native, Asian and Pacific Islanders, and Hispanic women. Hispanic refers to individuals who indicated Hispanic ethnicity regardless of racial group. From 2000 to 2009, breast cancer incidence rates declined among Whites, but have been statistically stable for the other racial/ethnic groups.7 Rates are per 100,000 persons and are age-adjusted to the 2000 U.S. standard population.3 Data for White and African American women are from the original nine SEER registries and were adjusted for reporting delays. Data for other races/ethnicities are from the 13 SEER registries. For Hispanic women, incidence data do not include cases from the Alaska Native Registry. Incidence data for American Indians/Alaska Native women are based on Contract Health Service Delivery Area (CHSDA) counties. Figure 3.1. Female breast cancer incidence rates by race and ethnicity 3-4 Breast Cancer and the Environment: Prioritizing Prevention 3 more likely to be diagnosed before age 4020 and with later stage breast cancer.7 Hispanic and Native American women also are diagnosed with later stage breast cancer compared to White women, suggesting that late-stage diagnosis is, in part, associated with racial/ethnic minority status23 and factors associated with that status, such as lower income and lack of health insurance.21, 22 For example, studies have shown that, compared to non-Hispanic White women, other racial/ethnic groups may have less access to mammograms.26, 27 Mortality from breast cancer is higher in persons with lower socioeconomic status (SES)28, 29 SES is an indicator for a constellation of other factors that potentially contribute to disparities in breast cancer, including availability and access to health care30 and exposure to environmental contaminants of potential relevance to breast cancer, such as endocrine-disrupting chemicals.8, 31, 32 the highest death rate from breast cancer despite a lower incidence rate than White women, as shown in Figure 3.2. This disparity may be due to more aggressive tumor biology, later stage at diagnosis, and/or factors related to access to care and receipt of optimal treatment.7, 20-23 Current evidence indicates that Black women are more likely than non-Hispanic White or Hispanic women to be diagnosed with tumors that have more aggressive features in the pathological examination and molecular marker assessment, such as TNBC,24 high-grade and TNBC,20 and basal-like breast cancer.25 Data from 2004 to 2007 also reveal that age-specific rates of IBC were higher for non-Hispanic Black women than for non-Hispanic White or Hispanic women.15 In addition, Black women are We need to know why some aggressive forms of breast cancer are more common in Black women. This figure displays female breast cancer death rates in the United States for the years 1990 to 2009 for White, Black, American Indian and Alaska Native, Asian and Pacific Islander, and Hispanic women. Hispanic refers to individuals who indicated Hispanic ethnicity regardless of racial group. Rates are per 100,000 persons and are age-adjusted to the 2000 United States standard population.3 Information is included for all states except Connecticut, Louisiana, Maine, Maryland, Minnesota, Mississippi, New Hampshire, New York, North Dakota, Oklahoma, South Carolina, Vermont, and Virginia, and the District of Columbia.3 Figure 3.2. Female breast cancer death rates by race and ethnicity 3-5 Breast Cancer and the Environment: Prioritizing Prevention 3 Seven percent of breast cancer patients develop a second breast cancer, usually in the opposite breast.41 Women with breast cancer have a 67 percent increased risk of a new breast cancer diagnosis during the first 10 years after the initial diagnosis compared to women in the general population.41 Established risk factors for developing a second primary breast cancer suggest a genetic influence and include: (1) a family history of breast cancer;42 (2) certain identified genetic characteristics;43 (3) breast density;42 and (4) early age at diagnosis.42 Additional risk factors are related to the treatment for the first breast cancer and include (1) having breast-conserving surgery but no radiation therapy;42 and (2) not having adjuvant treatment (a treatment in addition to the primary treatment).44 3.6 Survivorship On January 1, 2008, there were 2.6 million female breast cancer survivors in the United States.45 The estimated number is 3 million as of January 1, 2012.46 Treatment for breast cancer has improved substantially over time in terms of the success of the treatment, the opportunities to tailor