Système circadien et symptômes associés au cancer

The circadian timing system controls several temporal aspects of physiology and behaviour of animals and humans. A disruption of the circadian timing system results in alterations at different levels: central coordination, circadian physiology, molecular clocks and signaling pathways. In particular, the circadian disruption induced by long-haul flights or rotating night shift work is associated with the occurrence of systemic symptoms such as fatigue, mood and sleep disorders and anorexia. These symptoms, associated with circadian disruption, are also commonly experienced by cancer patients, as a result of their neoplastic disease or its treatment. The evidence from an in-depth scientific literature review supports the hypothesis that a disruption of the circadian timing system, before or during chemotherapy, is involved in the elicitation of systemic symptoms. Such circadian disruption further impairs quality of life and decreases chronotherapy safety and efficacy in cancer patients. Thus, an innovative therapeutic approach aiming at shielding and/or restoring the integrity of the circadian timing system ought to be proposed. This novel strategy should improve the therapeutic index of chemotherapy, through increasing its efficacy and decreasing its toxicity, while reducing symptom occurrence, maintaining quality of life and prolonging the survival of cancer patients. The implementation of such strategy relies upon non-invasive recording of circadian biomarkers, personalization of chronotherapy administration and circadian rehabilitation obtained through pharmacological and behavioural interventions.