Fatigue is the most common disorder experienced by patients during the cancer trajectory from diagnosis to the end of life. The proportion of patients experiencing fatigue reported to be between 40% and 100% of cancer patients. CRF has a negative impact on patients’ physical, psychological, social and existential wellbeing, with an impaired experience of quality of life. The syndrome degrades labor & daily activities, social relationships; the physiologic, behavioral, emotional, and cognitive components of fatigue affect tumor progression by disturbing mood state, willingness to receive treatment, daily life, feelings of security. Besides that CRF may interfere with therapy compliance and even limit the active antitumor treatment. These disturbances cause the survival worsening and increased mortality. Individuals may perceive fatigue as impaired physical performance, depletion of energy, a feeling of heaviness and tiredness or exhaustion, reluctance, being fed up, a need for reduced activity, reduced motivation (including lack of initiative, pessimism and not knowing what to do with oneself, expectation of negative outcome), and/or mental fatigue. The sickness behavior: irritability, loss of appetite, sleepiness, social withdrawal, anhedonia, as well as mood and cognitive disturbances - is well-known. As a moving force of this disorder cytokines were appreciated. An association between these inflammatory markers and fatigue in various nosologic forms of cancer patients was verified.  Higher levels of cytokines appear to be associated with a greater symptom burden. One more burden infers on patient’s feelings to the caregivers. It is such feelings that are highly correlated with CRF mood components: depression, hopelessness, outlook. Managing fatigue is a priority for comprehensive care in cancer. Early identification and symptom management has a key role in palliative care regarding the patients’ physical, psychosocial and existential needs. There’s need to develop an effective intervention targeting a single pathopsychophysiological  mechanism.

Keywords: Cancer, Fatigue, Physical manifestations, Mood disorders, Cytokines