SDOH Stress Creates Poor Breast Cancer Outcomes, Health Disparities

According to a recent study, heightened allostatic load due to social determinants of health stressors are linked to a lower likelihood of completing chemotherapy and a lower overall survival rate for patients with lymph node-positive or high-risk lymph node-negative HER2-negative breast cancer, creating potential health disparities.

Allostatic load is the “wear and tear” on the body caused by lifelong social determinants of health (SDOH) stressors, including social isolation, poverty, and racism — many factors that are common in minority populations.

An elevated allostatic load is associated with various health problems such as high blood pressure, increased body mass index, kidney disease, inflammation, arthritis, and other chronic conditions.

“Patient behavior and clinical outcomes cannot be isolated from the effects of their social environment,” surgical oncologist at The Ohio State University Comprehensive Cancer Center Samilia Obeng-Gyasi, MD, MPH, said in a press release. “Allostatic load provides us with a way to evaluate the effects of social and environmental stressors on a patient’s physiology.”

In the study, Obeng-Gyasi and colleagues in the ECOG-ACRIN Cancer Research Group researched if an allostatic load or genetic ancestry impacted patients’ survival and likelihood of completing chemotherapy.

Previous studies suggested that allostatic load and genetic ancestry both played roles in poor breast cancer outcomes; however, studies had yet to look at both factors at the same time to study population.

“We observed that people with a high allostatic load at the beginning of the study had a greater likelihood of stopping chemotherapy early and a higher risk of death,” said Obeng-Gyasi.

“In contrast, we did not observe an association between genetic ancestry and survival or chemotherapy completion. This suggests that allostatic load may be better than genetic ancestry at predicting chemotherapy completion and overall survival.”

The researchers analyzed data from the ECOG-ACRIN E5103 phase III clinical trial. It is one of the first breast cancer treatment trials to assemble a biorepository and database of patient information, including demographics and DNA.

The trial studied the effect of adding bevacizumab into sequential anthracycline and paclitaxel chemotherapeutic regimens in patients with lymph node-positive or high-risk lymph node-negative HER2-negative breast cancer.

Using genomic analyses and other patient information from the E5103 trial, the research team examined chronic stress, measured by allostatic load, across three broad categories of genetic ancestry. Among 348 patients included in the analysis, about 80 percent had European ancestry, 10 percent had African ancestry, and 10 percent had another ancestry.

The allostatic load was measured in patients in the E5103 trial using cardiovascular, immune, and metabolic systems biomarkers found before starting treatment. After adjusting for genetic ancestry, the researchers discovered that each 1 unit increase in allostatic load score resulted in a 15 percent reduction in the likelihood of completing chemotherapy and a 14 percent increase in the risk of death.

 “These results suggest that long-term exposure to chronic social and environmental stress may contribute to poor outcomes in patients with breast cancer,” said Obeng-Gyasi.

Obeng-Gyasi explained that by continuing research, measuring allostatic load could become a useful tool in predicting outcomes for breast cancer patients.

“Future prospective clinical trials with repeated measures of allostatic load may provide greater insight into its relationship to treatment and survival, especially if allostatic load is collected multiple times during the active treatment and survivorship phases of care,” Obeng-Gyasi added.

According to Obeng-Gyasi, a study limitation is that the analyses only included a subpopulation of patients with breast cancer, meaning the results may not apply to all patients. Additionally, the study used a small sample size.

The study was conducted by the ECOG-ACRIN Cancer Research Group and supported by the National Cancer Institute of the National Institutes of Health.