Circadian disruption, fatigue, and anorexia clustering in advanced cancer patients: implications for innovative therapeutic approaches.

A disruption of the circadian timing system, as identified by monitoring of marker biorhythms, is common in cancer patients. The recording of the rest-activity rhythm with a wrist actigraph has been commonly used. This noninvasive monitoring allows a robust estimation of circadian disruption. The authors have previously found that altered patterns of circadian rest-activity rhythms are significantly and independently associated with the severity of fatigue and anorexia in patients with metastatic colorectal cancer. Elevated proinflammatory cytokines could partly account for this circadian disruption and its associated constitutional symptoms. Here, the authors present and discuss the data supporting the hypothesis that circadian disruption is often associated with fatigue and anorexia, which in turn further alter and dampen circadian synchronization, thus, creating a vicious cycle. This body of evidence paves the path for innovative therapeutic approaches targeting the circadian timing system in an effort to diminish constitutional symptoms induced by cancer and some anticancer treatments.