Biological effects of ultrasonic cavitation in cancer therapy: from physics to mechanobiology.

The therapeutic efficacy of systemic treatments in cancer therapy is invariably limited by the biophysical barriers, including vascular endothelial barrier, extracellular matrix, and elevated interstitial fluid pressure. Ultrasonic cavitation, as a non-invasive modality, can induce a series of biological effects that leverage mechanical forces to breach these biophysical barriers and remodel the tumor microenvironment. This review traces the paradigm shift from thermal coagulation to mechanochemical modulation, where acoustic forces are transduced into profound biological responses via mechanosensitive ion channels and immunogenic signaling pathways. We summarize recent advances in the intelligent engineering of ultrasound-active materials, from vascular-targeted microbubbles and phase-change nanodroplets to oxygen-independent piezocatalysts. Meanwhile, we clinically evaluate the utility of cavitation in enhancing drug delivery and remodeling immune environment, and highlight the milestone approval of histotripsy for non-thermal ablation. Finally, we discuss critical challenges regarding stochasticity and biosafety, proposing a roadmap toward artificial intelligence-guided, closed-loop dosimetry. We predict that by integrating physical mechanics with biological engineering, ultrasonic cavitation may alleviate multidrug resistance and immunosuppression in cancer therapy.