UNC Study Supports Role Of Circadian Clock In Response To Chemotherapy
Posted Jan 19 2009 1:16am
For years, research has hinted that the time of day that cancer patients receive chemotherapy can impact their chances of survival. But the lack of a clear scientific explanation for this finding has kept clinicians from considering timing as a factor in treatment.
Now, a new study from the University of North Carolina at Chapel Hill has suggested that treatment is most effective at certain times of day because that is when a particular enzyme system – one that can reverse the actions of chemotherapeutic drugs – is at its lowest levels in the body.
The study, performed in mice, could also have implications for the prevention of new cancers.
The enzyme system implicated – called nucleotide excision repair– repairs many types of DNA damage that come not just from chemotherapy but also from the ultraviolet rays of the sun. Thus, by understanding the cyclical nature of this system, physicians may be able to pinpoint when it is most crucial for people to protect themselves from sun exposure to minimize their risk of skin cancer.
“Timing is everything, and here we have molecular data showing why this is especially true with regard to cancer,” said senior study author Aziz Sancar, M.D., Ph.D., a member of the UNC Lineberger Comprehensive Cancer Center and Sarah Graham Kenan professor of biochemistry and biophysics in the UNC School of Medicine. Sancar is also a member of the National Academy of Sciences and the Turkish Academy of Sciences. “By hitting cancer cells with chemo at a time when their ability to repair themselves is minimal, you should be able to maximize effectiveness and minimize side effects of treatment.”