Cancer treatment-related fatigue (CTRF) is a poorly understood condition with a profound effect on the quality of life for both the patient and the caregiver. Studies suggest that CTRF is the most undiagnosed and undertreated treatment-related symptom among cancer patients. Virtually 100% of cancer patients report symptoms of fatigue at some time during or following their cancer treatment, even months after treatment has concluded. These estimates include patients receiving chemotherapy, radiation or a combination of both. CTRF has been characterized by a total decrease in energy and wakefulness, and a disruption in patient diurnal rhythms. CTRF does not typically result from exertion or activity, nor is it alleviated by rest or sleep. Clearly, CTRF is not only a general sense of tiredness, but also a complete disruption in circadian rhythms.
Animal Models of Cancer Treatment-Related Fatigue
We have developed murine models of both chemotherapy- and radiation-induced CTRF, independent of anemia, in order to further understand its pathogenesis and provide a conduit for the development of mechanistically based therapeutic approaches. Infrared motion sensors are affixed to cage tops to continually measure locomotor activity. Unlike running wheel activity, which requires animals to perform specific voluntary activity, use of this monitoring system provides constant monitoring to evaluate sleep/wake cycle disturbances and changes. Treatment of animals with fractionated total body irradiation (fTBI) over a course of three weeks results in both a significant decrease in overall locomotor activity as well as a significant alteration in sleep/wake patterns. In the model of radiation-induced CTRF, fatigue is independent of bone marrow status, anemia and weight loss for a minimum of thirty days post radiation. Treatment of animals with a single dose of chemotherapy (etoposide sulfate) results in a significant dose-dependent decrease in overall locomotor activity eighty days after administration. Fatigue is not associated with symptoms of anemia or neutropenia.
As members of the American Association for Cancer Research (AACR), our Oncology Group has presented their own work at internationally recognized meetings, like the Supportive Oncology Conference.
