Circadian rhythms and cancer chemotherapy.

Experimental and clinical pertinent data regarding circadian rhythmicities are reviewed in (1) target tissues, i.e., healthy tissues (actively proliferating or not) and tumor tissues, (2) pharmacology of anticancer agents, (3) toxicity and tolerance of these agents and (4) antitumor activity of cancer chemotherapy. The basic concepts of chronotolerance and/or of chronoefficacy have brought new hopes for further amelioration in the management of cancer patients. Quite recent published Phase II and III clinical trials have demonstrated that new improvements on the therapeutic index have been achieved through ambulatory chronotherapy for various solid tumors.