Previous studies documented that African American women are more likely to be diagnosed with ER and/or PR negative breast tumors than whites. However, little is known about the effect of socioeconomic position and other tumor characteristics on the ER/PR tumor status differences between African American and whites. We studied this relationship using the National Cancer Database (NCDB).
The NCDB collects information on demographic and clinical characteristics for approximately 1,500 Commission on Cancer-approved hospitals, representing almost 70% of all cancer patients treated in the United States. We selected invasive breast cancer in women ages 18-99 years reported to the NCDB during 2004-2005. A total of 175,820 women diagnosed with breast cancer were available for the analysis after excluding those patients with missing ER/PR status. Frequency distributions were used to assess the relationships between hormone receptor status and demographic and clinical variables. Multivariate logistic regression models were used to examine these associations while controlling for age, race, insurance status, educational attainment, stage, histology, and tumor size.
African American women are 2.26 times more likely to be diagnosed with ER-PR- breast cancer vs. ER+PR+ breast cancer compared to whites. After controlling for socioeconomic factors, including educational attainment (based on patient’s zip code) and insurance status, African American women remained 1.97 times more likely to have hormone negative tumors than white women. Adjustment for tumor characteristics (stage, tumor size, and histology) further attenuated the odds ratio (RR=1.85). Lower educational attainment was associated with ER-PR- breast cancers. Women who were uninsured at the time of diagnosis were also more likely to have receptor negative disease compared to women with private health insurance, however, after adjusting for tumor characteristics this association was no longer significant.
Our results confirm previous reports which indicate African American women are more likely to be diagnosed with ER-PR- breast cancer. A third of this excess risk was explained by differences in socioeconomic factors, stage at diagnosis, tumor size, and histology type. Further studies with additional individual-level data on socioeconomic factors could help clarify these relationships.
Citation Information: Cancer Prev Res 2008;1(7 Suppl):B122.
Seventh AACR International Conference on Frontiers in Cancer Prevention Research-- Nov 16-19, 2008; Washington, DC