Understanding Disparities in TNBC may Help to Better Inform Practice and Policy

A study funded by the National Institute on Minority Health and Health
Disparities of the National Institutes of Health, published early online in CANCER, a peer-reviewed journal of the American Cancer Society, demonstrates that women of color and young women may face elevated risks of developing triple-negative breast cancers (TNBC), which are often aggressive and do not respond to hormone therapy or targeted therapy.[1]

Previous studies in the United States 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, Lia Scott, PhD, MPH, of the Georgia State University School of Public Health, and her colleagues analyzed all breast cancer cases diagnosed during 2010–2014 from the United States Cancer Statistics database, a population-based surveillance system of cancer registries with data representing 99% of the U.S. population.

Significant burden
The team identified 1,151,724 cases of breast cancer from 2010–2014, with triple-negative cases accounting for approximately 8.4% of all cases. The researchers uncovered a significant burden 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 2.3-times (OR, 2.27; 95% CI, 2.23-2.31) and 1.2-times higher odds (OR, 1.22; 95% CI, 1.19-1.25) of being diagnosed with triple-negative breast cancer, respectively.

More than 21% of non-Hispanic black women were diagnosed with triple-negative breast cancer, compared with less than 11% 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 (OR, 1.95; 95% CI, 1.90-2.01). Also, among women who were diagnosed with breast cancer, those diagnosed at late stages were 69% more likely to have triple-negative cancer than other types.

Lack of therapeutic options
The authors noted that due to 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.

Defined by the absence of estrogen and progesterone receptors and the absence of HER2 overexpression, triple-negative breast cancers represent a heterogeneous breast cancer subtype characterized by shorter overall survival (OS) and an early peak of distant recurrences at 3 years after diagnosis. The majority of deaths occur in the first 5 years following initial diagnosis. To date few systemic treatment options exist besides the use of chemotherapy. The heterogeneity of the disease has limited the successful development of targeted therapy. [2]

Better understanding
“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,” Scott said.

“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,” she concluded.

Reference
[1] Scott LC, Mobley LR, Kuo TM, Il’yasova D. Update on triple-negative breast cancer disparities for the United States: A population-based study from the United States Cancer Statistics database, 2010 through 2014.Cancer. 2019 Jul 8. doi: 10.1002/cncr.32207. [Pubmed][Article]
[2] Collignon J, Lousberg L, Schroeder H, Jerusalem G. Triple-negative breast cancer: treatment challenges and solutions. Breast Cancer (Dove Med Press). 2016 May 20;8:93-107. doi: 10.2147/BCTT.S69488. eCollection 2016. [PubMed][Article]