While a majority of cancer patients are already fatigued before they ever begin radiation therapy, almost all will have experienced it by the end of treatment.
Researchers at the University of Rochester had 370 radiotherapy patients fill out of a symptom inventory at the beginning of their radiation treatment and each week during therapy. Before therapy began 57% were fatigued. By the end of the third week, 76% were expressing fatigue. By the end of treatment 78% said that they were fatigued. Only 13% never experienced any fatigue at any point.
Of those 160 patients who were not fatigued at the beginning of treatment, 70% developed it during radiotherapy.
Prostate cancer patients reported the least severe fatigue while the most severe was experienced by patients with lung, gastrointestinal, and head and neck cancers. Age, sex, or radiation dose was not signficantly related to how severe fatigue was.
Jane Hickock M.D. and her team, in reporting their results in the October 15, 2005 issue of *Cancer* (Volume 104, Issue 8 , Pages 1772 – 1778), concluded:
Fatigue was a common adverse effect of RT for cancer, reported by more than three-fourths of patients by the third to fifth weeks of treatment. Cancer diagnosis was the only factor found to be significantly related to variation in fatigue severity. Additional studies should be devised to identify other underlying causes of RT-related fatigue
[Read the study abstract in *Cancer*.](http://www3.interscience.wiley.com/cgi-bin/abstract/111081990/ABSTRACT)