Differences in breast cancer stage at diagnosis between non-Hispanic white and Hispanic populations, San Diego County 1988-1993

The incidence of breast cancer in the U.S. is lower among Hispanic women than non-Hispanic white women. However, population-based studies show that Hispanic women are more likely to be diagnosed at a later stage than non-Hispanic whites. We aimed to determine whether: 1) a lower proportion of breast cancer was diagnosed at early vs. late stages in Hispanic compared to non-Hispanic white women from 1988-93 in San Diego County, and 2) lower income is related to later stage at diagnosis for both groups. All incident cases of breast cancer in San Diego County from the California Cancer Registry (10, 161 cases) were stratified by 'early' (in situ or localized) or 'late' (regional or distant) stage, and by race/ethnicity. Annual average age-adjusted incidence rates/100,000 (AAIR) were calculated. Incidence rate ratios (IRR) (AAIR for early stages divided by AAIR for late stages) were used as a surrogate of early detection. AAIRs for early and late stage disease were significantly higher for non-Hispanic whites (89.3, 42.3) than Hispanic women (46.7, 27.2). The IRR was significantly higher for non-Hispanic whites than Hispanics, (2.11 vs 1.72, p = 0.01). This difference was greatest among women under 50 years old (IRR difference 0.63), and not apparent for women 65 or older (IRR difference 0.06). There was also an association between increasing census tract per capita income and higher rates of early stage disease among non-Hispanic whites but not Hispanics. Results suggest that Hispanic women and lower income women should be targeted for early detection.