Breast cancer deaths have declined over the past 2 decades, with approximately half of the decrease estimated to be due to advances in early detection and treatment. However, not all racial groups have benefited equally from these advances. A recent report from the Centers for Disease Control and Prevention showed that black women have a higher death rate from breast cancer despite having a lower incidence.1
The report summarized findings from the United States Cancer Statistics dataset for 2005 to 2009, including mortality data from the National Vital Statistics System and incidence data from the National Program of Cancer Registries and the Surveillance, Epidemiology, and End Results program. Annual invasive breast cancer incidence and mortality rates for black women and white women were age-adjusted to the 2000 U.S. standard population. Staging data excluded cases identified only by autopsy or death certificate.
Incidence and Disease Stage
Among women of all races, an average of 205,246 cases of breast cancer was diagnosed each year from 2005 to 2009, with an annual average of 173,970 cases in white women and 21,942 cases in black women. Black women had an incidence rate of 116.9 cases/100,000 population, compared with 122.1/100,000 for white women (Fig. 1). However, cancer was more advanced at diagnosis in black women; 45% of cases in black women were at regional (37%) or distant (8%) stages, compared with 35% of cases in white women (30% regional, 5% distant). Rates per 100,000 population for black vs white women were 61.0 vs 75.7 for localized disease, 42.3 vs 36.8 for regional disease, and 9.6 vs 6.0 for distant disease.
Relative Mortality
Breast cancer mortality was 41% higher in black women, with mortality rates of 31.6 deaths/100,000 population in black women and 22.4/100,000 in white women. The mortality-to-incidence ratio was 0.27 in black women, representing 27 deaths per 100 breast cancer cases, compared with 0.18 in white women, representing 18 deaths per 100 cases.
A total of 40 states and the District of Columbia had a sufficient number of breast cancer deaths to be included in a by-state analysis of mortality-to-incidence ratio. The ratios for black women showed greater variability and were generally higher than those for white women; states reported ratios as high as 0.30 to 0.33 for black women, with no states reporting ratios this high for white women.
The authors noted that several factors likely contribute to the increased proportion of advanced cancers and higher mortality rate among black women. Some studies indicate lower mammography use and longer intervals between screening mammograms in black women. Black women also have longer times to diagnosis after an abnormal mammogram compared with white women. Black women are more frequently found to have tumor subtypes with a poorer prognosis, particularly triple-negative cancers.
Other studies indicate that black women do not receive the same quality of treatment for breast cancer, and it has been estimated that up to approximately 20% of the mortality difference between black women and white women could be eliminated if both populations received the same treatments. It has also been reported that a smaller percentage of black women begin treatment within 30 days of diagnosis compared with white women.
Steps to Eliminate Disparities
The authors concluded, “At the individual level, the maximal effectiveness of screening for breast cancer can only be achieved when all women have access to timely follow-up testing after abnormal breast cancer exams and state-of-the-art treatment. More research is needed to determine the best screening and treatment strategies for aggressive breast cancers. Optimal health-care delivery can be strengthened through performance-based reimbursement, expanded use of information technology, and quality assurance-reporting protocols. More work also is needed to develop, evaluate, and disseminate additional interventions to decrease inequities in follow-up after an abnormal mammogram and receipt of treatment.”
They note that the National Cancer Institute has recently funded a multisite program with the goal of supporting research to improve recruitment, screening, diagnosis, and referral to treatment for breast, colon, and cervical cancers. Additional information can be found at http://appliedresearch.cancer.gov/networks/prospr. ■
Reference
1. Centers for Disease Control and Prevention: Vital signs: Racial disparities in breast cancer severity—United States, 2005-2009. MMWR 61:922-926, 2012.
