ABSTRACT
Recent epidemiological evidence has linked circadian disruptions to several chronic conditions, including cancer. Experimental studies and clinical trials with cancer patients have shown that dysregulation of circadian rhythms acts as an important inducer and promoter of cancer, and/or exacerbating cancer symptom clusters and consequently decreasing the quality of life of the patients. Poor efficacy of cancer therapies and early mortality are also associated with loss of circadian control. In addition to altered expression of clock genes, which have been reported in several tumor types, the putative association between circadian disruption and cancer may be driven, at least in part, by immune system dysregulation and changes in the secretion of cytokines that influence inflammation. In cancer, circadian disruptions can also be associated with a reaction of the host’s physiology to the presence of tumors or a result of neuroimmunoendocrine responses to the physical and emotional demands associated with the disease that may affect the -neuroendocrine axis and circadian rhythms, contributing to cancer progression. A better understanding of the circadian rhythms in cancer patients can contribute to delineation of cancer prevention strategies as well as pharmacological and non-pharmacological treatments, besides providing novel biological and behavioral targets for more effective interventions.
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LCLJ and LCV have participated in study design and planning; elaboration and critical review of the manuscript; approval of the final version of the manuscript and have public responsibility for the content of the article.
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