Short-term statin treatment reduces, and long-term statin treatment abolishes chronic vascular injury by radiation therapy.

Background: The incidental use of statins during radiation therapy has been associated with a reduced long-term risk of developing atherosclerotic cardiovascular disease.

Objectives: Determine if irradiation causes chronic vascular injury and whether short-term administration of statins during and after irradiation is sufficient to prevent chronic injury compared to long-term administration.

Methods: C57Bl/6 mice were pretreated with pravastatin for 72 hours and then exposed to 12 Gy x-ray head-and-neck irradiation. Subsequently, they received pravastatin either for one additional day or for one year. Carotid arteries were tested for vascular reactivity and altered gene expression one year after irradiation.

Results: Treatment with pravastatin for 24 hours reduced the loss of endothelium-dependent vasorelaxation and protected against enhanced vasoconstriction after IR. It reduced the expression of some markers associated with inflammation and oxidative stress and modulated that of subunits of the voltage and Ca activated K (BK) channel in the carotid artery one year after irradiation. Treatment with pravastatin for one year completely reversed the changes caused by irradiation.

Conclusions: In mice, short-term administration of pravastatin is sufficient to reduce chronic vascular injury after irradiation. Long-term administration eliminates the effects of irradiation. These findings suggest that a prospective treatment strategy involving statins could be effective in patients undergoing radiation therapy. The optimal duration of treatment in humans has yet to be determined.