MONDAY, April 18 (HealthDay News) -- The long-term fatigue that affects breast cancer survivors may be caused by higher sympathetic and lower parasympathetic activity, according to a study published online March 9 in Psychoneuroendocrinology.
Christopher P. Fagundes, Ph.D., from The Ohio State University College of Medicine in Columbus, and colleagues examined the association between fatigue and both sympathetic and parasympathetic nervous system activity in 109 breast cancer survivors. The women had either finished treatment for stage 0-IIIA breast cancer in the previous two years or had undergone surgery, radiation, or chemotherapy at least two months earlier. Heart rate variability (HRV) and norepinephrine were measured at rest, during, and after a standard laboratory speech and mental arithmetic stressor.
The investigators found that women who reported higher fatigue had significantly lower HRV and higher norepinephrine before and after the stressor than women who reported being less fatigued. Fatigue was not correlated with treatment, type of treatment, time since treatment, cancer stage, or time since diagnosis. Fatigued women were more likely to be unmarried, have a lower socioeconomic status as indexed by education, have a marginally higher body mass index, and report more depressive symptoms, all previously identified correlates of fatigue.
"Fatigue is a notable clinical problem in cancer survivors, and understanding its pathophysiology is very important," the authors write. "Our data suggest that HRV and norepinephrine could be important biomarkers for cancer-related fatigue and may have an etiological role."