For everything -- including chemo -- there is a time

Doctors often wonder if there is a best time of day for cancer patients to receive chemotherapy. Past research suggests there probably is an optimal time based on the body's circadian rhythms. Now, a compelling new study offers some biological proof for the idea. Researchers at the University of North Carolina have discovered that chemotherapy is probably most effective at particular times of day when an enzyme system in the body that can blunt the impact of the drugs is at its lowest levels. The enzyme system is called nucleotide excision repair. It works to fix DNA damage from toxic substances, like chemotherapy agents, but also DNA damage from sun exposure. The study is one of the most convincing pieces of evidence that the body's internal time-keeping system, which resides in every cell, can affect the potency of some drugs. The study is part of a growing interest among scientists to understand the impact of circadian rhythms on human health , as was described in this recent story in ... (link)