Racial differences in breast cancer stage at diagnosis in the mammography era

Abstract

Objectives: We assessed racial differences in breast cancer mortality by stage at diagnosis, since mammography became available.

Methods: We calculated adjusted odds of distant (versus local or regional) tumors for 143,249 White and 13,571 Black women aged 50 to 69 years, diagnosed with breast cancer between 1982 and 2007 and living in a Surveillance, Epidemiology, and End Results region. We compared linear trends in stage at diagnosis before and after 1998.

Results: Distant-stage cancer was diagnosed in 5.8% of White and 10.2% of Black participants. The Black-White disparity in distant tumors narrowed until 1998 (1998 adjusted difference = 0.65%), before increasing. Between 1982 and 1997, the proportion of distant tumors decreased for Blacks (adjusted odds ratio [AOR]/y = 0.973; 95% confidence interval [CI] = 0.960, 0.987) and Whites (AOR/y = 0.978; 95% CI = 0.973, 0.983), with no racial differences (P = .47). From 1998 to 2007, the odds of distant versus local or regional tumors increased for Blacks (AOR/y = 1.036; 95% CI = 1.013, 1.060) and Whites (AOR/y = 1.011; 95% CI = 1.002, 1.021); the rate of increase was greater for Blacks than Whites (P = .04).

Conclusions: In the mammography era, racial disparities remain in stage at diagnosis.

FIGURE 1—

Proportion of advanced-stage disease at time of breast cancer diagnoses and self-reported rates of mammography in the past 2 years among White and Black women over time (a) unadjusted analysis and (b) adjusted analysis. Sources. Surveillance, Epidemiology, and End Results 9 database, 1982–2007, for main data; Behavioral Risk Factor Surveillance System, 1992–2006, for mammography rates.