Circadian chronotherapy for human cancers.

Cell physiology is regulated by a 24-hour clock, consisting of interconnected molecular loops, involving at least nine genes. The cellular clock is coordinated by the suprachiasmatic nucleus, a hypothalamic pacemaker which also helps the organism to adjust to environmental cycles. This circadian organisation brings about predictable changes in the body's tolerance and tumour responsiveness to anticancer agents, and possibly also for cancer promotion or growth. The clinical relevance of the chronotherapy principle, ie treatment regimens based upon circadian rhythms, has been demonstrated in randomised, multicentre trials. Chronotherapeutic schedules have been used to document the safety and activity of oxaliplatin against metastatic colorectal cancer and have formed the basis for a new approach to the medicosurgical management of this disease, which achieved unprecedented long-term survival. The chronotherapy concept offers further promise for improving current cancer-treatment options, as well as for optimising the development of new anticancer or supportive agents.