Ultrasound Radiation Force for Increased Transport of Drugs in Cancer Tumors

Abstract

Cancer is today one of the leading causes of death world wide. Chemotherapy is a cancer treatment where cytotoxic drugs are administered intravenously in order to kill the cancer cells. This is a therapy form which is widely used, although it has large side effects and thereby greatly reduces the quality of life for the patients. Some of the main challenges with chemotherapy is that a large fraction of the dose is distributed in healthy tissue, and that the drug does not reach all cells in the tumor. Ultrasound waves generate a radiation force on the medium they propagate through. This force acts similar to a pressure gradient and can enhance transport of macromolecules from the capillaries and through the extracellular matrix (ECM) in tumors. By encapsulating the drug in larger particles, one can limit the concentration of drugs in healthy tissue, while ultrasound radiation force can enhance the concentration in the tumor. An in vivo experiment to investigate this effect was planned and conducted. Simulations of ultrasound waves that propagate through water and tissue show that appropriate ultrasound transducers can generate large radiation forces and potentially increase transport from capillaries to central regions of solid tumors significantly. However, the results from the conducted in vivo experiment must be analysed before any conclusions can be drawn. These results were not available during writing.