Racial/ethnicity disparities in invasive breast cancer among younger and older women: An analysis using multiple measures of population health.

Introduction: Few studies have examined age and racial/ethnic disparities in invasive breast cancer among younger (age 15-44 years) vs. older (age 45-64 years) women. This study estimates disparities in breast cancer among younger compared with older women by race/ethnicity using five measures of population health: life expectancy (LE), expected years of life lost (EYLL), cumulative incidence rate (CIR), and incidence and mortality rate ratios (IRR and MRR).

Methods: Using Surveillance, Epidemiology, and End Results data, LE and EYLL were estimated from a cohort of 15-44 and 45-64 years, non-Hispanic black (NHB), non-Hispanic white (NHW), and Hispanic women diagnosed with breast cancer, 2000-2013. Survival function was obtained from the study years and then extrapolated to lifetime using the Monte Carlo method. The CIR, IRR and MRR were calculated using 2009-2013 breast cancer incidence and mortality rates from the Centers for Disease Control and Prevention's National Program of Cancer Registries.

Results: The estimated LE ranged from 32.12 to 7.42 years for localized to distant stages among younger NHB women compared to 33.05 to 9.95 years for younger NHW women. The estimated EYLL was 12.78 years for younger women, and 4.99 for older women. By race/ethnicity, it was 15.53 years for NHB, 14.23 years for Hispanic and 11.87 years for NHW (P<0.00025). The CIR for age-group 15-44 years (CIR) indicated a 1 in 86 probability for NHB compared to a 1 in 87 probability for NHW being diagnosed with breast cancer by age 45. The estimated age-adjusted incidence rate for NHB-to-NHW women was IRR=1.10 (95%, CI=1.08-1.11) and the corresponding mortality rate was MRR=2.02 (95%, CI=1.94-2.11).

Conclusions: The breast cancer disparities between younger NHB compared to NHW women highlight the need for expanded efforts to address these disparities through primary prevention and to improve access to quality healthcare to minority women with breast cancer.