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Pharmacy Links

AFTER CANCER: POSTCANCER FATIGUE (SYMPTOM, CAUSE)

March 12, 2009

Is Postcancer Fatigue the Same As Chronic Fatigue or Chronic Fatigue Syndrome?

No. Postcancer fatigue is a symptom distinct from chronic fatigue and that seen in chronic fatigue syndrome. “Postcancer fatigue” applies only to weariness that occurs in people in remission following treatment, that is due to the prior cancer or its treatment, and that persists after all treatable causes of fatigue have been ruled out or been corrected.

In contrast, “chronic fatigue” is a term that describes a symptom but conveys nothing about its cause, course, or treatment. “Chronic fatigue syndrome,” still a somewhat controversial concept, is defined not only by its unique symptom complex but also by the supposed causative agents, the usual course it takes, and the treatment.

What Causes Postcancer Fatigue?

Although the exact mechanism remains unknown, the scientific community accepts the view that residual effects of radiation, chemotherapy, or other cancer therapy can cause fatigue long after the completion of treatment. Since the definition of postcancer fatigue demands that all treatable causes of tiredness have been ruled out or corrected, as-yet-unidentified changes or abnormalities are the probable culprits. Three possible causes are

•the circulation of fatigue-causing substances released by dead, dying, or repairing cells

• changes in the parts of the brain that affect energy level, changes caused by prior cancer or treatment

• the residual inefficiency of otherwise normal cells and organs (e.g., muscles may appear normal on examination and with diagnostic tests but may be functioning subnormally as a result of changes on the cellular level, detectable only with sophisticated research technology)

Fatigue is a nonspecific symptom. It is difficult, if not impossible, to determine which of the hard-to-quantify possible causes are playing a role. You may have been treated optimally for depression; yet some residual refractory depression (depression unresponsive to treatment) persists. Or you may have a high risk of recurrent cancer, and chronic subclinical anxiety (it is present, but there is little sign of it) may be contributing to your fatigue. We need further study of the mechanisms of this symptom. The hope is that research will lead to effective means of prevention, detection, and treatment of postcancer fatigue.

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