Racial Differences in Breast Cancer Stage at Diagnosis in the Mammography Era

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.Despite a lower incidence of invasive breast cancer, Black women in the United States are more likely than are White women to die of the disease.1,2 Since 1992, although breast cancer deaths have declined in both White and Black women, the overall disparity in mortality has increased.3 Stage at diagnosis is the strongest predictor of survival in breast cancer,4–6 and Black women are more often diagnosed with advanced-stage disease than are White women.7–10Mammography is an important tool in the early detection of breast cancer.11–13 First introduced in the United States in the early 1980s,14 mammography was initially most prevalent among White women. Racial disparities in mammography rates narrowed by the mid-1990s,12,15 and Black women had rates equivalent to or greater than those of White women between 1996 and 2000.10,15,16 From 2000 to 2005, mammography use declined nationally in women aged 50 to 64 years (78.6% to 71.8%), with a slightly larger decrement for White (−4.0%) than Black (−3.3%) women.13The survival benefit of any screening program, including mammography, is related to its ability to detect tumors at earlier stages. Meta-analyses continue to find mortality benefit for mammography, although uncertainty remains regarding both the appropriate target population and the optimal screening interval.11,17,18 Consistent with the expected effect of screening, an observational cohort analysis found that improvements in screening rates for both Black and White women during the 1990s contributed to diagnosis at an earlier stage in both groups.10Nevertheless, despite generally equivalent rates of mammography for the past 15 years, the racial disparity in breast cancer mortality between Black and White women persists. Although previous meta-analyses suggested a mortality benefit for mammography, randomized controlled data regarding the efficacy of screening programs in minority populations are limited.18,19 Because stage at diagnosis is an important predictor of survival in breast cancer, we assessed temporal changes in the distribution of stage at diagnosis between 1982 and 2007, in both Black and White women, adjusting for covariates known to affect stage at diagnosis.