Breast Cancer: Autonomic Nervous System Malfunction May Cause Fatigue

By Jody Smith HERWriter

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Breast cancer survivors deal with exhaustion. This is no surprise. For about one-third of these survivors however, this exhaustion can continue to sap them for up to a decade after the cancer is history.

According to an April 6, 2011 Eurekalert! public release, a cause of this fatigue may have come to light. The autonomic nervous system (ANS) may be to blame.

This ANS malfunction can cause such depletion that a survivor's aging process accelerates to the point that she can seem 20 years older than her actual age.

A 30-year study from the Ohio State University College of Medicine in Columbus, Ohio studied 109 breast cancer survivors who had completed treatment for stage 0-111A breast cancer in the previous two years or had had chemotherapy, radiation or surgery at least two months prior.

The autonomic nervous system is made up of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).

The sympathetic nervous system is famed for its fight-or-flight response. The parasympathetic nervous system is not so well known, perhaps due to its laid-back nature. PNS is the system of rest and regeneration.

When things are working properly, the SNS and PNS trade off as needed. In times of stress or when extra push is wanted, the SNS steps up. When the crisis is averted, when the deadline has been achieved, things settle down under the gentle care of the PNS.

Problems arise when for one reason or another the sympathetic nervous system is triggered too often and stays activated too long.

Researchers studied breast cancer survivors struggling with long-term fatigue, and survivors who were not. Testing indicated that women dealing with long-term fatigue spent more time with an activated SNS and less time with an activated PNS.

This configuration may be a marker for systemic inflammation, a known cause for extreme fatigue as so much energy is dedicated to fighting infection.

The fatigued women had higher levels of the stress hormone norepinephrine and lower heart rate variability (HRV). Lower HRV is linked to high blood pressure and cardiovascular disorders.

Lee Jones observed that fatigue of this caliber has a higher incidence with breast cancer than other cancers. Jones is the scientific director of Duke Cancer Institute's Center for Cancer Survivorship in Durham, NC. He speculated that a contributing factor might be some breast cancer drugs which can harm the heart, consequently adversely affecting energy levels.

The study was funded in part by the American Cancer Society and the National Institutes of Health. This research was published on March 9, 2011 in an online issue of Psychoneuroendocrinology.

Sources:

Eurekalert! Breast cancer patients' persistent fatigue is real, may actually speed up aging
http://www.eurekalert.org/pub_releases/2011-04/osu-bcp040611.php

MedicineNet.com: Nervous System Imbalance May Cause Fatigue in Breast Cancer Survivors
http://www.medicinenet.com/script/main/art.asp?articlekey=143089

MDNews.com: Post-Cancer Fatigue Linked to Autonomic Nervous System
http://www.mdnews.com/news/hd/2011_17/hd_651802

Reviewed August 8, 2011
by Michele Blacksberg R.N.

Visit Jody's website and blog at http://www.ncubator.ca and http://ncubator.ca/blogger

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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.