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Constant immune system activity could cause fatigue in breast cancer survivors
Women with persistent fatigue had 30% more proinflammatory cytokine protein in their blood.
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Breast cancer survivors who suffer from persistent, debilitating fatigue years after their diagnosis have something in common: their immune systems fail to shut down following treatment, according to a recent study.
This constant immune system activation, discovered by measuring specific proteins in blood samples from survivors, may be causing the fatigue. This discovery could lead to the use of behavioral interventions, such as Tai Chi and yoga, which will help alleviate persistent fatigue. Chronic fatigue affects about one-third of breast cancer survivors for years after they complete treatment.
“Without knowing why this fatigue happens at the cellular level, we can’t develop efficient therapies to treat it,” said Michael Irwin, MD, from the University of California, Los Angeles Jonsson Comprehensive Cancer Center.
“Breast cancer survivors can be severely disabled by fatigue and that can dramatically impact their quality of life,” said Irwin, who is also director of the Cousins Center for Psychoneuroimmunology at the Semel Institute for Neuroscience and Human Behavior at UCLA. “Right now, we have no treatment for cancer-related fatigue and we need something that will allow patients to return to their prior level of functioning.”
Irwin and colleagues measured the levels of a proinflammatory cytokine protein in blood samples from breast cancer survivors one to five years after diagnosis.
Survivors with persistent fatigue had 30% more of the proteins circulating in their blood. Additionally, their immune cells produced more cytokines in laboratory analyses than the cells from survivors without fatigue, and those cytokines more efficiently produced the proinflammatory proteins driving the immune response.
The immune systems of women undergoing treatment for breast cancer are activated at high levels to help them fight disease and help the body recover from the side effects of chemotherapy and radiation. Some data suggest that survivors who develop fatigue might have immune system changes before the onset of cancer. Treatments could exacerbate those immune system changes, according to Irwin.
Behavioral interventions
The proinflammatory proteins could be used as a biomarker to classify those women who may suffer from fatigue after treatment. In those who appear to be predisposed to fatigue it may be possible to provide immediate interventions that might eliminate or alleviate the severity and duration of the fatigue.
Physicians can intervene with immunosuppressive drugs like statins or they can recommend behavioral interventions like Tai Chi and yoga. Exercise and meditation have been shown to decrease levels of proinflammatory cytokine expression in the blood, according to Irwin.
Editor’s note: A not uncommon phenomenon associated with breast cancer (even before its detection) is autoimmune paraneoplastic neuropathy. Patients so affected seem to have higher cure rates, presumably related to a heightened immune response to tumor cells. It would be interesting to know whether this subgroup might also manifest greater postremission fatigue as well. – Harry S. Jacob, MD, FRCPath (Hon)
For more information:
- Collado-Hidalgo A, Bower JE, Ganz PA, et al. Inflammatory biomarkers for persistent fatigue in breast cancer survivors. Clin Cancer Res. 2006;12:2759-2766.