Background: It has been postulated that different biologic characteristics of a tumor might account for at least a portion of the disparity in breast cancer survival for patients across racial and ethnic groups. The hormone receptor status of breast tumors is one characteristic with prognostic significance. Results of several studies indicate a higher proportion of estrogen receptor negative (ER-) breast tumors among black or Hispanic women compared with non-Hispanic whites. We investigated whether the association between race and ethnicity and the joint combination of ER and progesterone receptor (PR) status was independent of age and other tumor characteristics at diagnosis.
Methods: Relevant data were obtained from 13,239 breast cancer cases identified as part of the 1990 Patient Care Evaluation Study of Breast Cancer.
Results: In univariate analysis, the proportions of ER+PR+, ER+PR-, ER-PR+, and ER-PR- tumors among non-Hispanics whites were 59%, 15%, 6%, and 20%, respectively; among Hispanics the proportions were 58%, 12%, 8%, and 22%, respectively; and among blacks the proportions were 44%, 14%, 7%, and 35%, respectively. After controlling for age, tumor size, and histology, using polychotomous logistic regression, these was no difference in hormone-receptor status between Hispanic and non-Hispanic white women. However, ER-PR- tumors were more likely to occur in blacks than in non-Hispanic whites (odds ratio = 1.8, 95% confidence interval = 1.6, 2.1)
Conclusions: The results of this study corroborate differences in hormone-receptor status between non-Hispanic white and black women, but not between Hispanics. Future studies of breast cancer should examine differences in epidemiologic risk factors between blacks and whites stratified on ER/PR status.