Fatigue usually has multiple factors.
There are primary factors including the intensity, development and stage of the illness.
Secondary factors linked to cancer include weight fluctuation, chronic pain, anxiety/depression, anemia (inflammatory or induced by treatments), difficulty sleeping (insomnia), and malnutrition.
Fatigue is also caused by factors linked to treatments including surgery (usually shorter in duration), chemotherapy (which can sometimes last several years after the treatment has been completed) and cerebral radiotherapy. Sometimes, it is not the treatment itself, but the frequent visits to the hospital, with travel and waiting time, which cause excessive fatigue.
Physical deconditioning, comorbidities (neurological, cardiovascular, endocrinal – such as hypothyroidism) and the patient’s psychosocial state can also significantly impact fatigue levels.