Women of color and young women may face elevated risks of developing triple-negative breast cancers, a type of cancer that spreads more quickly than most other types and doesn't respond well to hormone or targeted therapies, a study published in CANCER, a peer-reviewed journal of the American Cancer Society, shows.
Previous U.S. studies have found racial disparities in triple-negative breast cancer diagnoses, but few have looked beyond the scope of one state. To conduct a larger study, researchers in the Georgia State University School of Public Health analyzed all breast cancer cases diagnosed during 2010-14 from the United States Cancer Statistics database, a surveillance system of cancer registries with data representing 99 percent of the U.S. population.
The team identified more than 1.15 million cases of breast cancer, with triple-negative cases accounting for about 8.4 percent of all cases. The researchers uncovered a significant incidence of triple-negative breast cancer for women of color, specifically non-Hispanic black women, and for younger women.
Compared with non-Hispanic white women, non-Hispanic black women and Hispanic women had higher odds of being diagnosed with triple-negative breast cancer, respectively. More than 21 percent of non-Hispanic black women were diagnosed with triple-negative breast cancer, compared with less than 11 percent for all other types of breast cancer. Women younger than 40 years of age had twice the odds of being diagnosed with triple-negative breast cancer than women aged 50-64 years. Also, among women who were diagnosed with breast cancer, those diagnosed at late stages were 69 percent more likely to have triple-negative cancer than other types.
"Our results demonstrate that African American women of younger age are more likely to be diagnosed with triple negative breast cancer than younger women of other ethnicities," said Dora Il'yasova, epidemiologist and associate professor in the School of Public Health at Georgia State.
Because of the aggressive nature of triple-negative breast cancer and the lack of therapeutic options, it is important to know which individuals face a higher risk and what factors may influence this risk, the researchers noted.
"Until we have evidence of what environmental and genetic components contribute to this risk, it is imperative that women know their familial history of breast cancer, discuss that with their physicians and follow screening recommendations," said Lia Scott, lead researcher, recent doctoral graduate of the Georgia State University School of Public Health (Ph.D. '18), and current Steven M. Teutsch Prevention Effectiveness Fellow with the Centers for Disease Control and Prevention Division of Cancer Prevention & Control. "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."
According to the American Cancer Society, most breast cancers are mainly classified by three proteins that can affect the cancer's growth: the estrogen hormone receptor, the progesterone hormone receptor and the human epidermal growth factor receptor 2 (HER2). Triple-negative breast cancer does not have any of the receptors, making it difficult to identify what is fueling the cancer's growth. Doctors have fewer options for targeted treatment to destroy these cancer cells. Chemotherapy is still an effective option for treating this cancer and reducing the risk of its return.
The study's co-investigators are Lee Rivers Mobley, associate professor of spatial population science and health economics in the School of Public Health; Dora Il'yasova, associate professor of epidemiology and biostatistics in the School of Public Health; and Tzy-Mey Kuo, a senior statistical analyst with the Integrated Cancer Information and Surveillance System initiative at the University of North Carolina's Lineberger Comprehensive Cancer Center.
This study was funded by the National Institute on Minority Health and Health Disparities of the National Institutes of Health.
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.