Effects of radiation on cutaneous microvascular function in the intact human circulation

Abstract

Radiation treatment for cancer is associated with an increased risk of cardiovascular disease. Animal studies report decreases in endothelial vasodilator function in radiated arteries, however, there remains limited knowledge about the intact human circulation. Therefore, the aim of the present study was to determine the acute and chronic effects of radiation therapy on cutaneous microvascular reactivity in breast cancer patients. METHODS: The present study utilized a cross-sectional study design in 7 breast cancer patients receiving radiation therapy and 13 survivors > 3 years post-radiation therapy. Cutaneous microvascular reactivity to acetylcholine (ACh) was evaluated following radiation exposure at the site of radiation treatment and at a contralateral control non-radiated site. Red blood cell flux was measured as an index of cutaneous blood flow via laser Doppler flowmetry with ACh-mediated vasodilation determined by iontophoresis drug delivery. Cutaneous vascular conductance (CVC) was calculated by normalizing for mean arterial pressure. RESULTS: %CVC to incremental ACh was significantly attenuated in the radiated compared to non-radiated tissue following a total cumulative dose of 2104±236 cGy within the patients currently receiving radiation. In the survivors (6475±70 cGy) there were no differences between radiated and non-radiated tissue. However, the peak %CVC in the cancer survivors was significantly lower compared to the non-radiated tissue of the cancer patients. CONCLUSION: This study demonstrates that radiation for cancer treatment attenuate cutaneous microvascular function, which could have long-term implications for cardiovascular health.