Cancer patients undergoing radiation and chemotherapy may be able to minimize their hair loss merely by receiving treatment later in the day, new research suggests.
 

A team of scientists — from the Salk Institute for Biological Studies, the University of Southern California, and the University of California, Irvine — determined hair growth in mice follows a 24-hour cycle of growth and restorative repair. In new research published online in the Proceedings of the National Academy of Sciences, the team found mice lost 85 percent of their hair if they received radiation therapy in the morning, compared to a 17 percent loss when treatment occurred in the evening.

Special: This Small Group of Doctors is Quietly Curing Cancer
 

The researchers suspect human hair growth follows a similar daily pattern and that hair loss from toxic cancer radiotherapy and chemotherapy might be minimized if treatments are given late in the day.
 

"These findings are particularly exciting because they present a significant step towards developing new radiation therapy protocols that include minimizing negative side effects on normal tissues, such as hair or bone marrow, while maintaining the desired effects on cancer cells," said lead researcher Maksim Plikus, assistant professor of developmental and cell biology at UCI. "We will now apply our findings to design novel circadian rhythm-based approaches to cancer therapy."
 

The scientists said human organs and tissues have their own biological clocks that, if understood, could be used to time drug therapy for maximum benefit.
 

"There are clocks everywhere in the body — clocks that have their own unique rhythm that, we found, have little to do with the central clock in our brains," said co-researcher Satchidananda Panda, an associate professor in Salk's Regulatory Biology Laboratory and an expert on circadian rhythm.
 

"This suggests that delivering a drug to an organ while it is largely inactive is not a good idea. You could do more damage to the organ than when it is awake, repairing and restoring itself. If you know when an organ is mending itself, you might be able to deliver more potent doses of a drug or therapy. That might offer a better outcome while minimizing side effects."
 

The study was funded, in part, by the National Institutes of Health.