Increasing Black:White disparities in breast cancer mortality in the 50 largest cities in the United States

Introduction: This paper presents race-specific breast cancer mortality rates and the corresponding rate ratios for the 50 largest U.S. cities for each of the 5-year intervals between 1990 and 2009. Methods: The 50 largest cities in the U.S. were the units of analysis. Numerator data were abstracted from national death files where the cause was malignant neoplasm of the breast (ICD-9 = 174 and ICD-10 = C50) for women. Population-based denominators were obtained from the U.S. Census Bureau for 1990, 2000, and 2010. To measure the racial disparity, we calculated non-Hispanic Black:non-Hispanic White rate ratios (RRs) and confidence intervals for each 5-year period. Results: At the final time point (2005–2009), two RRs were less than 1, but neither significantly so, while 39 RRs were >1, 23 of them significantly so. Of the 41 cities included in the analysis, 35 saw an increase in the Black:White RR between 1990–1994 and 2005–2009. In many of the cities, the increase in the disparity occurred because White rates improved substantially over the 20-year study period, while Black rates did not. There were 1710 excess Black deaths annually due to this disparity in breast cancer mortality, for an average of about 5 each day. Conclusion: This analysis revealed large and growing disparities in Black:White breast cancer mortality in the U.S. and many of its largest cities during the period 1990–2009. Much work remains to achieve equality in breast cancer mortality outcomes.