Changes in the racial disparity in breast cancer mortality in the ten US cities with the largest African American populations from 1999 to 2013: The reduction in breast cancer mortality disparity in Chicago.

PURPOSE: Assess progress made to reduce racial disparity in breast cancer mortality in Chicago compared to nine other cities with largest African American populations and the US. METHODS: The Non-Hispanic Black (NHB) and Non-Hispanic White (NHW) female breast cancer mortality rates and rate ratios (RR) (disparity) were compared between 1999 and 2005 and 2006 and 2013. RESULTS: Between the two periods, the NHB breast cancer mortality rate in Chicago decreased by 13.9% (95% CI [-13.81, -13.92] compared to 7.7% (95% CI [-7.52, -7.83]) for NHW. A drop of 20% in the disparity was observed, from 51% (RR: 1.51, 95% CI [-7.52, -7.83]) to 41% (RR: 1.41, 95% CI [1.30, 1.52]). Whereas from 1999 to 2005 Chicago's disparity was above that of the U.S., from 2006 to 2013, it is now slightly lower. For the remaining nine cities and the US, the mortality disparity either grew or remained the same. CONCLUSIONS: Chicago's improvement in NHB breast cancer mortality and disparity reduction occurred in the context of city-wide comprehensive public health initiatives and shows promise as a model for other cities with high health outcome disparities.