Inflammation and neural signaling: Etiologic mechanisms of the cancer treatment-related symptom cluster

Purpose of review Cancer patients undergoing treatment with cytotoxic chemotherapeutic agents (CCAs) often experience a cluster of treatment-related symptoms, which include fatigue, loss of appetite, disturbed sleep, depressed mood, cognitive difficulties, and changes in body composition. This symptom cluster collectively referred to herein as cancer treatment-related symptoms (CTRSs) decrease quality of life, and physical and social functioning. The preclinical and clinical studies described in this review represent important progress in understanding potential underlying mechanisms of CTRS. Recent findings Recent studies support a role for CCA-induced interleukin-1b (IL-1β) signaling in the cause of CTRS. CCAs may share a common ability to activate intracellular stress response pathways to trigger the synthesis, processing, and release of IL-1b from immune cells. Fatigue, sleep disturbance, and cognitive difficulties in cancer patients exposed to CCAs correlate with plasma levels of IL-6, IL-1 receptor antagonist, and soluble tumor necrosis factor receptor-I/II, surrogate markers of IL-1β-mediated central nervous system (CNS) inflammation. Additional preclinical work suggests IL-1β-mediated CNS inflammation may cause CTRS by altering hypothalamic and hippocampal functioning. Summary Although additional research is necessary to further establish the link between CCA exposure, IL-1bmediated inflammatory processes and CTRS, these data provide hints for future studies and therapeutic approaches in ameliorating these symptoms in cancer patients.