Abstract B84: Increasing disparities in breast cancer mortality for young black women in the U.S. from 1979-2010
Authors: McCarthy Anne Marie , Yang Jianing , Armstrong Katrina 
Published: May 2015

Introduction: Though cancer mortality rates have declined in recent years, black women still have 40% higher breast cancer mortality rates than whites. In addition, black women and are more likely to be diagnosed with breast cancer before age 45 and to be diagnosed with later stage and more aggressive tumors. The purpose of this study was to examine mortality trends among black and white women younger than 50, comparing trends in racial disparities in breast cancer mortality to trends in mortality from other common cancers and cardiovascular disease (CVD).

Methods: The CDC's Mortality Multiple Cause of Death Files were used to obtain cause specific death counts among women aged 20-49 years from 1979-2010. This data file includes information from US death certificates reported to the National Center for Health Statistics. Cause-specific mortality rates were calculated using underlying cause of death counts and U.S. Census intercensal population estimates for each year. Mortality rates were age standardized to the 2000 Standard Population using the direct method. ICD-9 and ICD-10 codes for cancer, CVD, breast cancer, cervical cancer, colorectal cancer, lung cancer, ischemic heart disease, and cerebrovascular disease (stroke) were reconciled using CDC guidelines. Since Hispanic ethnicity was not a required field on death certificates until 1989, race/ethnicity was categorized as black or white prior to 1989, and non-Hispanic white or non-Hispanic black for 1989 onward. Mortality rate-ratios were calculated comparing age-standardized mortality rates for blacks to those of whites.

Results: Though mortality rates from both cancer and CVD declined from 1979-2010, black women aged 20-49 had significantly higher mortality rates than whites. In 2010, the cancer mortality rate was 40.6 per 100,000 among blacks compared to 28.8 per 100,000 among whites and the CVD mortality rate was 42.7 per 100,000 among blacks compared to 16.6 per 100,000 among whites. For CVD, the mortality rate-ratio comparing blacks to whites declined from a peak of 4.01 in 1989 to 2.57 in 2010. In contrast, the mortality rate-ratio was more stable for cancer, with a peak mortality rate-ratio of 1.58 in 1998 compared to 1.41 in 2010. Black women had higher mortality rates from breast cancer, colorectal cancer, cervical cancer, ischemic heart disease, and stroke compared to white women over the entire study period. Blacks had higher lung cancer mortality than whites through 2008, and similar or lower mortality rates 2009-2010. The mortality rate-ratio decreased over the study period for ischemic heart disease, stroke, cervical cancer and lung cancer. The mortality rate-ratio increased slightly for colorectal cancer through 2000, and declined after 2000. The mortality rate-ratio increased for breast cancer, from 1.36 in 1979 to 2.00 in 2010.

Conclusions: Though mortality rates have declined over the past 30 years for women under 50, significant disparities in the two leading causes of death, cancer and CVD, remain. The persistence of disparities across diseases highlights the need to focus on improving health outcomes broadly, in addition to disease centered approaches, in order to prevent premature deaths among young women. The breast cancer mortality rate was two times greater among black women younger than 50 compared to white women, indicating a more profound disparity in younger women than older women. Furthermore, while relative disparities have decreased over time for most of the causes of death examined, the disparity in breast cancer mortality appears to be widening among young women. We plan to further quantify these trends using joinpoint regression to calculate the average percent change in mortality rates over time.

Citation Format: Anne Marie McCarthy, Jianing Yang, Katrina Armstrong. Increasing disparities in breast cancer mortality for young black women in the U.S. from 1979-2010. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B84. doi:10.1158/1538-7755.DISP13-B84