Odds of triple-negative breast cancer (TNBC) are elevated for minority women and younger women, results of a nationwide cross-sectional cohort study of more than a million breast cancer cases confirm.
Previous studies have suggested certain sociodemographic groups are disproportionately affected by TNBC, but have been limited by the population studied, size, and characteristics assessed, note the investigators, who were led by Lia C. Scott, PhD, MPH, of the division of epidemiology and biostatistics at the School of Public Health, Georgia State University, Atlanta. “It is imperative that cancer research identify factors that drive disparities and focus on prevention,” they wrote in Cancer.
Dr. Scott and coinvestigators used the United States Cancer Statistics database to identify 1,151,724 cases of breast cancer diagnosed during 2010-2014 in 39 states having the necessary data. TNBC accounted for roughly 8.4% of all cases.
In unadjusted analyses using non-Hispanic white women as the comparator, odds of TNBC were significantly higher for non-Hispanic black women (odds ratio, 2.27), Hispanic women (OR, 1.22), and American Indian/Alaska Native women (OR, 1.26). On the other hand, odds were lower for Asian women (OR, 0.92).
By age group, compared with women 50-64 years old, women younger than 40 years were most likely to have the TNBC phenotype (OR, 1.95), while women aged 75 or older were least likely (OR, 0.75). Odds of TNBC were also significantly elevated for women whose cancer was diagnosed at stage III or higher (OR, 1.69) or at stage IV (OR, 1.47).
Findings were essentially the same in analyses simultaneously adjusted for age, race, and stage.
“The results of the current study demonstrated that there is a significant burden of disease in TNBC diagnosed among women of color, specifically non-Hispanic black women, and younger women,” Dr. Scott and coinvestigators write. “Given the large sample size and geospatial coverage of the data, these results are somewhat different from and also more generalizable, compared with data from previous studies.”
“With the advent and availability of more comprehensive cancer data, such as the United States Cancer Statistics database, it is important that we continue to explore disparities in order to better inform practice and policy around screenable cancers like breast cancer,” she further commented in a statement. “We hope that this update on the epidemiology of triple-negative breast cancer can provide a basis to further explore contributing factors in future research.”
Dr. Scott disclosed that she received a Dissertation Training Grant (F31-Diversity) from the National Institutes of Health. The study was funded by the National Institute on Minority Health and Health Disparities of the National Institutes of Health; the Centers for Disease Control and Prevention’s National Program of Cancer Registries contributed funds to cover the standard research data center fees for researchers conducting analyses under approved research projects.
SOURCE: Scott LC et al. Cancer. 2019 Jul 8. doi: 10.1002/cncr.32207.