Researchers at the University of Illinois Chicago examined national data about women with early-stage, estrogen receptor-positive breast cancer and found that social determinants of health and tumor biology contributed equally to higher rates of death among Black women.
The study, published in JAMA Oncology, is the one of first studies of breast cancer disparities to include a genomic biomarker of tumor aggression in the analysis of the proportion of the disparity mediated by tumor biology.
For their analysis, the researchers reviewed data available through the National Cancer Institute’s Surveillance, Epidemiology and End Results Program. They looked at stage 1 and stage 2 estrogen receptor-positive breast cancers, the most common type of breast cancer that generally has the most favorable prognosis, with cases that were diagnosed between 2004-2015.
Data from 60,137 Black and non-Hispanic white women were included in the study.
The researchers calculated the effect of social determinants of health — specifically neighborhood disadvantage and insurance status — on mortality and found they accounted for 19% of the disparity. They also calculated the effect of biological characteristics of the tumors by looking at data from genomic laboratory test results, which were used to anticipate tumor response to chemotherapy and likelihood of recurrence. They found tumor biology accounted for 20% of the disparity.
They also found, similar to many other studies, that white women were more likely than Black women to be in the highest income and education groups and in the lowest poverty group, and to have health insurance. Black women were more likely to have aggressive tumors with a high risk of recurrence, to be diagnosed at stage 2 and to receive chemotherapy.
