Os ritmos circadianos em câncer e a cronoterapia

Abstract

Circadian rhythms, physiological periods of about 24 hours, coordinate the temporal processes of most, or maybe all, living beings on the planet. Cell proliferation, one of the most important events in the body, is also regulated by the biological clock, whose alteration may have a direct impact on cancer development. The concept of chronotherapy comes from evidence showing that both cell proliferation and the mechanisms responsible for pharmacokinetics and pharmacodynamics of antineoplastic drugs occur at specific times of the day. This review presents an overview of the circadian cycle and its relation to cell cycle and cancer. Also, it presents evidence for the use of chronotherapy in patients with acute lymphocytic leukemia and in randomized clinical trials for colon, endometrial and ovarian cancer. As a conclusion, the time of chemotherapy administration should take into account the circadian rhythms of patients. We emphasize on the need to conduct clinical trials focused on chronomodulated chemotherapy, in order to increase the tolerance and effectiveness of drugs under the existing protocols.