is not yet clear, women treated with chemotherapy for breast cancer, for example, show subtle declines in global cognitive functioning, most particularly in language skills (e.g., word-finding ability), short-term memory, and spatial abilities; lesser impairment is found in their working and long-term memory and their speed of information processing (Stewart et al., 2006). Similar impairment of verbal memory and other executive cognitive functions has been found in adults treated for lung, colorectal, lymphoma, and other types of cancer; however, different types of cancer and their treatment vary in their cognitive effects (Anderson-Hanley et al., 2003).
Fatigue is the most frequently reported symptom of cancer and is identified as causing the greatest interference with patients’ daily activities, although estimates of rates of fatigue among individuals with cancer vary greatly (ranging, for example, from 4 percent in breast cancer patients prior to the start of chemotherapy to 91 percent in breast cancer patients after surgery and chemotherapy and before bone marrow transplantation). Prevalence rates are difficult to interpret, however, because there is no consensus on a standard definition of fatigue, and studies use different criteria for defining its presence and severity. Fatigue is theorized to arise from a complex combination of poorly understood physical and psychological effects of illness that may be different in each patient (Carr et al., 2002). Nonetheless, it is widely recognized as a frequent side effect of both cancer and its treatment. It is different from the fatigue experienced by healthy individuals in that it persists even after rest and sleep. A 2002 review of the evidence by the Agency for Healthcare Research and Quality (AHRQ) found that mechanisms of cancer-related fatigue have been poorly explored, and current treatment options for fatigue are limited5 (Carr et al., 2002). Fatigue among non-ill individuals generally is manifested by compromised problem solving, decreased motivation and vigor in the completion of required tasks, and overall diminished capacity for work (IOM, 2004). These effects are reported by patients with cancer as well, who also report that fatigue interferes with their physical and mental functioning (Carr et al., 2002).