IT’S WIDELY KNOWN that chronic stress takes a toll on health. But stress can also feel like a vague concept. Researchers have developed a way to quantify chronic stress using allostatic load, a measure that gauges the wear and tear the body experiences from multiple sources. Since the concept was first introduced in 1993, elevated allostatic load has been associated with higher mortality, including from cardiovascular disease, in several studies.
Applying this research to the field of oncology, Samilia Obeng-Gyasi, a surgical oncologist who studies health equity at Ohio State University Comprehensive Cancer Center–Arthur G. James Cancer Hospital and Richard J. Solove Research Institute in Columbus, recently published two studies that show elevated allostatic load is associated with poor cancer outcomes in patients with metastatic lung cancer and nonmetastatic breast cancer.
Cancer Today recently spoke with Obeng-Gyasi about her research.
CT: How did you become interested in this area of research?
OBENG-GYASI: My brother, Emmanuel Obeng-Gyasi, is an associate professor of environmental health, and he looks at allostatic load and cardiovascular disease. And we were talking once on the phone about our research, and I asked him, “What’s allostatic load?” And then I became interested. I said, “I wonder if people have looked at this concept in cancer.”
CT: What is allostatic load?
OBENG-GYASI: Allostatic load describes biological markers that have been used to represent stress. It’s composed of biomarkers from lab values, so [levels of] albumin or creatinine or hemoglobin A1C, and then also other vital signs like blood pressure, heart rate, height and weight. The way that we calculate the composite score is to use the biomarkers I described to quantify that stress by coming up with a number, essentially.
The hypothesis is that when somebody faces a stressor, the body activates a stress response, which goes through the hypothalamic-pituitary-adrenal axis. It also causes the release of cortisol, which has several downstream effects. One of them, for example, could be an elevation in your blood sugar, or another example could be an elevation in your blood pressure. What this conceptually argues is that having persistent elevation in your blood pressure or persistent elevation in your blood sugar can result in illnesses like hypertension or diabetes. The idea is that chronic exposure to socioenvironmental stressors could cause the stress response in your body to be chronically activated, which can then result in the development of certain types of disease processes, or possibly, if you are predisposed to those disease processes, may push you toward developing them.
CT: Is allostatic load measured in different ways?
OBENG-GYASI: There are many ways to measure it, but most of the measurements are coming from various components of the stress response. Typically, people use things like primary mediators, such as cortisol, which is one of the primary biomarkers from the stress response. People may also use what are called secondary outcomes, which are downstream effects of the primary mediators. These include things like blood pressure, heart rate and lab values. And then we have tertiary outcomes that are further downstream, which are actual disease processes, like hypertension and diabetes. Most studies tend to use secondary outcomes because those are easily accessible. For example, you can find them in the medical record. And things like cortisol level measurements sometimes are difficult to get. But there is no gold standard.
CT: Which populations have the greatest allostatic load?
OBENG-GYASI: Studies have shown that individuals who face historical and current marginalization tend to have higher allostatic load than those who do not. For example, some studies have shown women have higher allostatic load than men. Some studies have shown that individuals who are racialized as Black have a higher allostatic load than those who are racialized as white, or individuals who identify with Hispanic ethnicity may have a higher allostatic load than those who do not.
CT: What can be done to reduce allostatic load?
OBENG-GYASI: One study in China looked at expressive group therapy, a form of psychosocial support that consisted of weekly education and discussion sessions, for women with metastatic breast cancer. The study found that patients who participated in those activities had a lower allostatic load than those in a control group. And then there was a study at Georgetown University in Washington, D.C., by Dr. Lucile Adams-Campbell that looked at patients who don’t have breast cancer but have a higher risk of getting breast cancer. In that study, they had people do either supervised or unsupervised exercise, while a control group received no intervention. Those who participated in either exercise intervention were able to reduce their allostatic load. So, studies show that psychosocial support and exercise might be avenues to reduce allostatic load.
This interview has been edited and condensed for clarity.
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