Cancer remains a leading cause of death in the U.S., and while treatments such as chemotherapy and ultrasound can be effective, they often damage healthy tissue. A major challenge is delivering enough therapy to tumors without increasing toxicity. Solid tumors are particularly difficult to treat because their dense structure limits drug penetration and treatment effectiveness. In a new study, researchers have shown that tumors can be mechanically softened using sound, potentially making them easier and safer to treat.

Researchers at the University of Colorado Boulder (Boulder, CO, USA) have developed a treatment strategy that pairs high-frequency ultrasound with specially engineered, sound-responsive microscopic particles. These particles are designed to respond mechanically when exposed to ultrasound energy. The particles are made of silica and coated with a layer of fatty molecules. When exposed to high-frequency ultrasound, they vibrate rapidly and vaporize surrounding water, creating tiny bubbles. This localized physical activity alters the tumor’s microenvironment without directly damaging surrounding healthy tissue.

To test the approach, the researchers introduced the particles into tumor tissue cultures and applied ultrasound. In three-dimensional tumor models, the treatment reduced the amount of structural proteins surrounding tumor cells. This led to measurable softening of the tumor tissue. By lowering protein density in the tumor environment, the method improved the internal transport pathways within tumors. The findings, published in ACS Applied Bio Materials, demonstrate that mechanical tumor modification can be achieved without increasing ultrasound intensity or drug dosage.

Softening tumors could allow drugs, immune cells, or ultrasound energy to penetrate tumors more effectively. This approach may reduce the dose of chemotherapy or ultrasound required, lowering the risk of side effects. The strategy could be particularly useful for localized cancers such as prostate or bladder cancer. The researchers believe the technique could integrate with existing focused ultrasound systems already used clinically. Future work will explore how this approach performs in more complex models and how it can be combined with existing cancer therapies.

“Tumors are kind of like a city. There are highways running through, but it’s not laid out very well, so it’s hard to get through,” said Associate Professor Andrew Goodwin, senior author of the study. “The technology for focused ultrasound has come a really long way in the last decade. I'm hoping that the particles we build in the lab can start to meld with the acoustic, imaging, and therapy technologies that are part of the clinical regimen.”

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