Allostatic Load May Predict Likelihood to Complete Chemotherapy, Overall Survival in Certain Patients With Breast Cancer

Elevated allostatic load—defined as the negative effects lifelong exposure to stressors can cause on the body—was associated with a lower overall survival rate in patients with lymph node-positive or high-risk lymph node-negative human epidermal growth factor receptor 2 (HER2)-negative breast cancer, according to data presented at the 14th American Association for Cancer Research Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved. The presenters said these patients were also less likely to complete chemotherapy.

Allostatic load is caused by a number of different stressors, including social isolation, poverty, and racism, many of which are commonly experienced by individuals belonging to racial and ethnic minorities, according to the investigators. Elevated allostatic load has been associated with high blood pressure, increased body mass index, kidney disease, inflammation, and arthritis. Prior studies have also suggested allostatic load and genetic ancestry are both influential in poor breast cancer outcomes.

“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 Samilia Obeng-Gyasi, MD, MPH, a surgical oncologist at The Ohio State University Comprehensive Cancer Center, in a press release. “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.”

In the study, allostatic load was measured using biomarkers of the cardiovascular, immune, and metabolic systems collected prior to starting treatment for lymph node-positive or high-risk lymph node-negative HER2-negative breast cancer. These biomarkers included body-mass index, blood pressure, creatinine, and several cytokines.

“Patient behavior and clinical outcomes cannot be isolated from the effects of their social environment,” Obeng-Gyasi said in the release. “Allostatic load provides us with a way to evaluate the effects of social and environmental stressors on a patient’s physiology.”

According to the investigators, a 1 unit increase in a patient’s allostatic load score was associated with a 15% reduction in the likelihood of completing chemotherapy and a 14% increase in the patient’s risk of death. Future research may help establish allostatic load as a useful tool for predicting which patients with breast cancer may have an increased risk for stopping chemotherapy early, and function as a predictor of poor survival.

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

REFERENCE

Chronic stress may impact treatment completion and survival outcomes in patients with breast cancer [news release]. EurekAlert; October 6, 2021. Accessed October 6, 2021. https://www.eurekalert.org/news-releases/930239