Breast Cancer Disparities: Socioeconomic Factors versus Biology

Author: Newman, LA

Source: Ann Surg Oncol (2017) 24:2869-2875

https://www.ncbi.nlm.nih.gov/pubmed/28766222

While differences in breast cancer incidence and outcomes among AA versus WA women are frequently discussed, HA women are included less often. As this population increases in size, more information becomes available to study. The author of this paper explains current knowledge about the epidemiology and biology of breast cancer in AA and HA women in the US.

Life expectancy, rates of life-threatening conditions (such as diabetes, hypertension, and obesity) and overall cancer survival are lower among medically underserved populations. Americans in lower socioeconomic groups consistently have poorer health outcomes compared to their wealthier counterparts, and these differences are directly connected to having less access to healthcare.  

AA and HA women are more likely to have economic disadvantages compared to WA women, and that leads to significant differences in breast cancer outcomes. AA and HA women tend to have less access to screening mammography, and are also subjected to delays in breast cancer diagnosis. As a result, AA and HA women are more likely to present with advanced breast cancer stages. Many studies also show that AA and HA women are less likely to receive guideline-directed breast cancer care.

Socioeconomics are not the only cause for differences in breast cancer outcomes. There is increasing knowledge about the role of biology. The heritage of HA women is diverse, as ancestry may be of European, Native American, Central or South American and/or African origin. This awareness means that data collection for these women must be very detailed. Current research has found differences in incidence of triple negative breast cancer (TNBC) (TNBC is breast cancer whose cell receptors are not sensitive to estrogen, progesterone or Her2 neu)  among HA women depending upon European versus African heritage: women of the former group had lower rates of TNBC. Other studies have found that Native American ancestry is protective against breast cancer.  Findings like these contribute to observations of lower rates of breast cancer incidence and death among the HA population.

The role of biology in breast cancer among AA women is also being discovered. The rates of TNBC are higher in this ethnic group. AA women are also more likely to present with breast cancer at younger ages. Controlling for economics and stage at diagnosis, AA women still have worse outcomes. These facts appear connected to the recent theories that AA people are more likely to inherit genetic mutations that increase breast cancer risk. Moreover, AA are frequently descendants of West Africans via the slave trade. This region of the continent has a high rate of TNBC. This information helps to explain the observed worse outcomes of breast cancer among AA women.

Although socioeconomics undeniably plays a role in breast cancer detection and treatment for AA and HA women, underlying biology is also important. While it remains important to equalize healthcare access, it is equally important to continue to study biologic differences among groups. All of this information makes it increasingly impossible to attribute breast cancer outcomes to a single factor for AA or HA women.