Prognosis among African-American women and white women with lymph node negative breast carcinoma

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Abstract
A disparity in breast carcinoma survival between African-American and white women has been noted over the past several decades. A major factor implicated in this disparity is stage of disease at diagnosis. In this study, survival and related endpoints were examined among African-American women and white women with lymph node negative breast carcinoma who participated in two randomized clinical trials of the National Surgical Adjuvant Breast and Bowel Project (NSABP). Patients from two studies, one conducted among patients with estrogen receptor (ER) negative tumors and the other among patients with ER positive tumors, were included. Study goals were to determine whether African-Americans and whites had comparable outcomes, accounting for ER status and differences in patient characteristics at diagnosis, and to determine whether treatment response was similar for African-Americans and whites. Five-year survival rates were 83% for African-Americans and 85% for whites among ER negative patients, and 93% for African-Americans and 92% for whites among ER positive patients. Rates of disease free survival (DFS) (i.e., time to disease recurrence, second primary cancer, or death) were 71% for African-Americans and 74% for whites at 5 years among ER negative patients, and 81% for African-Americans and 80% for whites among ER positive patients. African-Americans tended to have less favorable baseline prognostic characteristics. Adjusted relative risk (RR) estimates indicated similar prognosis for African-Americans compared with whites for mortality (African-American/white RR = 1.02 with 95% confidence interval [CI], 0.66-1.56 among ER negative patients; RR = 1.14 with 95% CI, 0.84-1.54 among ER positive patients) and DFS (RR = 0.98 with 95% CI, 0.70-1.37 for ER negative patients; RR = 0.96 with 95% CI, 0.75-1.22 for ER positive patients). Estimated percent reductions in DFS events for patients receiving adjuvant therapy were 32% for ER negative African-Americans, 36% for ER negative whites, 20% for ER positive African-Americans, and 39% for ER positive whites. African-American and white patients with localized breast carcinoma had similar outcomes and benefited equally from systemic therapy. These results suggest that early detection and appropriate therapy among African-American patients could result in a reduction in the current disparity in breast carcinoma mortality between African-Americans and whites. Cancer 1997; 80:80-90. ©; 1997 American Cancer Society.