An ultrasound-based therapy known to agitate blood vessels has now been shown to enhance the tumor-blasting effects of radiation by 10-fold in experiments. The treatment, ultrasound-mediated excitation of microbubbles (micron-sized spheres of chemically inert gas), sensitized mouse tumors to radiation therapy.
After mice bearing prostate tumors received intravenous injections of microbubbles, the areas of injection were exposed to a microbubble-bursting frequency of ultrasound waves. When some of the tumors were subsequently subjected to ionizing radiation, the combination treatment increased tumor cell death by approximately 10 times more than radiation treatment alone.
The combination treatment with ultrasound and radiation appears to trigger programmed cell death (apoptosis) in cells lining the tumor blood vessels, reducing blood flow and ultimately inducing death of the tumor cells.
“We envisage this unique combined ultrasound-based vascular perturbation and radiation treatment method being used to enhance the effects of radiation in a tumor, leading to greater tumor eradication,” stated the investigative team, led by radiation oncologist Gregory J. Czarnota of the Sunnybrook Health Sciences Center in Toronto, Ontario, Canada, in Proceedings of the National Academy of Sciences of the United States of America (2012;109:E2033-2041).
As the researchers pointed out, with ultrasound and radiation boosting the effects of radiation, radiation doses can be reduced significantly.