Rates of breast cancer vary by race and ethnicity. Whites have the highest rates, followed by African Americans, Asian Americans/Pacific Islanders, Hispanics/Latinas and American Indian/Alaskan Natives (see Figure 1.5) [3,4].
Why the differences in breast cancer rates? The biggest reason seems to be that different races and ethnicities simply have different prevalence rates of the established risk factors for breast cancer [43]. Among other factors, age at first period, age at menopause, age at first birth, number of children and postmenopausal hormone use vary by race and ethnicity and impact breast cancer risk [181]. For example, compared to Hispanic/Latina women, white women are more likely to put off childbirth and to have fewer children, each of which increases the risk of breast cancer [43,181,182].
African American ethnicity
Although white women have higher rates of postmenopausal breast cancer compared to African American women, African American women have higher rates of premenopausal breast cancer [183-186]. There are a few possible reasons for this. African American women appear to have more reproductive factors related to breast cancer risk such as an earlier age at first period, more lifetime periods and higher blood estrogen levels [187-190].
There is growing evidence that there are biologic differences in the breast cancers of whites and of African Americans. Breast cancers in African American women are more likely to be higher grade, hormone receptor negative and have a greater number of mutations in the p53 gene—all factors linked to a worse prognosis [181,191,192]. These factors are also common among the basal-like/triple negative subtype of breast cancer. Triple negative breast cancers are estrogen receptor-negative, progesterone receptor-negative and HER2/neu-negative. These tumors have a poorer prognosis compared to other molecular subtypes. Although the reasons are not clear at this time, basal-like/triple negative tumors are more common among African American women compared to other women [193-197]. (For more on the molecular subtypes of breast cancer, see the Diagnosis section.)
For more information on rates of breast cancer by race and ethnicity, visit the Breast Facts section.
For more on differences in breast cancer rates in the U.S. and across the world, visit the Breast Facts section.
Updated 11/10/09
