An Explorative Study on Physiological and Neurophysiological Determinants of Fatigue in Cancer Survivors

Postcancer fatigue is a severe and invalidating problem, impairing quality of life. About 20 to 40% of the patients remain fatigued, at least one year after successful cancer treatment. Fortunately, there is an effective treatment for postcancer fatigue; cognitive behavior therapy. However, no cause for postcancer fatigue has been identified yet. The aim of the study is to identify factors that (partly) cause postcancer fatigue to improve the theoretical understanding of fatigue and to improve the diagnostics of fatigue, predict therapy outcome, and facilitate other treatment options. In this study, disease-free fatigued cancer patients, who finished treatment for cancer at least one year and maximally ten years ago, will be approached for this study. They will be compared to non-fatigued patients. First, a baseline assessment will take place. Magnetic resonance imaging of the brains will be performed to assess brain volume and magnetic resonance spectroscopy will be performed to measure the concentrations of specific substances in the brains. Changes in the volume of parts of the brains have been observed in (non-cancer) patients with the chronic fatigue syndrome (CFS), in comparison with healthy controls. In addition, abnormal concentrations of specific substances have been observed in patients with CFS compared to healthy controls. To assess muscle fatigue, a two-minute endurance test of the upper arm will be administered at maximal voluntary contraction. Next to differences in the brains, CFS patients showed (central) muscle fatigue. A maximal exercise test on a bicycle will be performed to assess physical fitness. Physical activity in fatigued cancer survivors is decreased, compared to healthy controls. It is not known whether physical deconditioning originated during the cancer treatment is the reason why these patients are still less active. In addition, patients and controls will wear an actometer for two weeks to register baseline daily physical activity