In a world's first, Sunnybrook researchers show strong potential to increase the tumour-destroying effects of cancer radiotherapy at lower doses of radiation by using ultrasound in a new way.
Ultrasound is typically used for imaging. Microscopic bubbles or "microbubbles" pass harmlessly through the body's circulation and are normally used as a contrast agent to allow ultrasound to detect cancers or the new growth of blood vessels indicating angiogenesis, critical for tumour growth.
In this study, the researchers for the first time use ultrasound to cause microbubbles to resonate inside tumour blood vessels of preclinical models to destabilize structures, creating greater sensitivity to smaller doses of radiation and amplifying the tumour cell-death inducing effects of radiation treatment.
Findings show a 40 to 50 per cent tumour volume cell death after a single 2 Gy radiation dose combined with ultrasound and microbubble treatment given in advance, compared to 5 per cent cell death using ultrasound and microbubble treatments or 2 Gy radiation treatment alone. Normally up to thirty-five 2 Gy treatments must be given to achieve comparable amounts of cell death.
The findings were published July 9 in the Proceedings of the National Academy of Sciences U.S.A.