Decline in US breast cancer rates after the Women's Health Initiative: Socioeconomic and racial/ethnic differentials

Objectives. We investigated whether there were socioeconomic and racial/ ethnic disparities in recent reported declines in overall US breast cancer incidence rates attributed to post-2002 declines in hormone therapy use following publication of the Women's Health Initiative study. Methods. We analyzed 1992-2005 US breast cancer incidence data from the US Surveillance, Epidemiology and End Result (SEER) 13 Registries Database, stratified by race/ethnicity, county income level, age, and estrogen receptor (ER) status. Results. As we hypothesized, between 1992 and 2005, the temporal pattern of rising and then falling US breast cancer incidence rates occurred only among White non-Hispanic women who lived in high-income counties, were aged 50 years and older, and had ER-positive tumors. No such trends were evident-regardless of county income level, ER status, or age-among Black non-Hispanic, Asian/Pacific Islander, Hispanic, or-where numbers were sufficient to conduct meaningful analyses-American Indian/Alaska Native women. Conclusions. The recent decline in US breast cancer incidence was not equally beneficial to all women, but instead mirrored the social patterning of hormone therapy use. Joint information on socioeconomic resources and race/ethnicity is vital for correctly understanding disease distribution, including that of breast cancer.