Fatigue in Breast Cancer Survivors Possibly Caused by Nervous System Imbalance

A recent study suggests that persistent fatigue, exhaustion, and other symptoms experienced by breast cancer survivors may be linked to an imbalance of the nervous system. Even in patients who have undergone successful treatments, fatigue and exhaustion can manifest as a result of a sort of tug of war between the “fight or flight” and “resting” responses of the central nervous system, with the former constantly being active and the latter unable to disengage it. This back and forth results in what is essentially a constant state of post-adrenaline drain, which causes severe exhaustion in many patients.

Breast Cancer Survivors

The study was conducted at Ohio State University, with one hundred and nine women split into two groups. All the women in the study had completed breast cancer treatment two years previous, and were divided into those who did and did not experience long-term, persistent fatigue. Those studied were tested for baseline levels of norepinephrine (a stress hormone) in the blood, and were asked to give a five-minute speech as well as answer a series of verbal math problem. Both tasks were designed to increase stress levels.

The study found that stress levels rose in both groups after these exercises, although those that did not experience persistent fatigue after breast cancer treatment had lower stress levels than those that were chronically tired. Study author Christopher Fagundes, a postdoctoral fellow at Ohio State University’s Institute of Behavioral Medicine Research, says that the researchers are not sure whether the fatigue is induced by stress. He qualifies this by adding that cancer and the treatment it requires can be a highly stressful event, which could indicate that stress can contribute to the changes in the autonomic nervous system. This pivotal research will help medical experts in their search for reliable biomarkers for cancer related fatigue and exhaustion symptoms.

The researchers found that breast cancer survivors that experience chronic fatigue and exhaustion (which occurs in roughly thirty percent of patients) experienced an imbalance between the two aspects of the autonomic nervous system: the sympathetic system, which is responsible for the fight or flight reflex, and the parasympathetic system, which conserves energy during resting periods. Lee Jones, scientific director of Duke Cancer Institute’s Center for Cancer Survivorship in Durham, N.C., said that this relationship between cancer treatment and chronic fatigue is something that the medical community has been aware of for some time, but that to date not much has been known about it. He adds that the recent study will contribute to the literature documenting the interplay between stress and cancer treatments, and that the chronic fatigue symptoms are seen more rarely with other types of cancer. According to Jones, this is likely because of the fact that breast cancer medications can be toxic to the heart, and can have a detrimental effect on long term levels of energy.