African-American ethnicity, socioeconomic status, and breast cancer survival: a meta-analysis of 14 studies involving over 10,000 African-American and 40,000 White American patients with carcinoma of the breast.

BACKGROUND: African-American women are at increased risk for breast cancer mortality compared with white American women, and the extent to which socioeconomic factors account for this outcome disparity is unclear.
METHODS: A MEDLINE search was conducted to identify published studies that used a Cox proportional hazards regression model to evaluate the outcome of African-American women and white American women with breast carcinoma after adjusting for socioeconomic status. A meta-analysis was performed using specialized statistical software; the random-effects method of statistical evaluation was used because of the a priori impression that the studies reviewed would be at least moderately heterogeneous in study design and patient populations.
RESULTS: The initial literature search yielded 3962 studies. Fourteen studies met all criteria for inclusion in the meta-analysis, resulting in a sample size of 10,001 African-American patients and 42,473 white American patients with breast carcinoma. There was substantial variation in the method used for defining socioeconomic status. Summary statistics revealed a significant odds ratio of 1.22 (95% confidence interval, 1.13-1.30) for the adverse effect of African-American ethnicity on breast cancer mortality. Subset meta-analyses yielded similar results, supporting the robustness of this finding.
CONCLUSIONS: This meta-analysis revealed that African-American ethnicity is an independent predictor of a worse breast cancer outcome. The pooled analysis has added strength because of the aggregate sample size and indicates that the true biologic and/or therapeutic determinants of disparities in breast cancer outcome for different ethnic groups and for different socioeconomic strata are incompletely understood. Copyright 2002 American Cancer Society.