Ultrasound partially destroys cancerous tumors in rats
The transducer used during histotripsy.
Non-invasive sound treatment destroys liver tumors in rats, eliminates cancer cells and stimulates the immune system to prevent further spread, say American scientists.
The treatment reduced liver tumor volume by 50% to 75%, and then the rats' immune systems cleared the rest, with no signs of recurrence or metastasis in more than 80% of the animals, the authors note. work published in the journal Cancers (in English).
Even if we do not target the entire tumor, we still manage to make it regress, but also to reduce the risk of formation of metastases, explains in a press release the biomedical engineer Zhen Xu, who has been developing the technique since 2001 with colleagues at the University of Michigan.
Professor Zhen Xu and student Tejaswi Worlikar around an ultrasound array transducer.
The technique is called histotripsy. Histos means cloth in ancient Greek, and tripsis, friction or grinding.
Medicine has used ultrasound for decades in ultrasounds, which use sound waves to produce images of the inside of the body, which helps doctors make diagnoses. Researchers at the University of Michigan are the first to test these waves in a treatment.
Histotripsy could sooner or later be added to the treatment options that require precise ablation and removal of certain tissues in the case of cancers or neurological diseases. Moreover, the method is currently the subject of a clinical trial (#HOPE4LIVER) conducted with about forty participants in order to verify its interest in treating liver cancer in humans.
Histotripsy allows the mechanical breakdown of tissue structure using a number of short, high-intensity sound pulses. Ultrasound concentrates energy towards a target with millimeter precision, which does not damage the surrounding tissues.
Our transducer emits ultrasound pulses […] called acoustic cavitations that bombard the tumor to break it up, says Xu.
These pulses generate microbubbles in targeted tissues that rapidly expand and retract. These violent, but extremely localized mechanical stresses end up killing the cancerous cells and breaking the structure of the tumour.
The targeted tissues eventually die without having the harmful side effects associated with surgery, radiotherapy or chemotherapy.
The intensity of the ultrasound used is hundreds of times greater than that of current ultrasounds. It resembles that of lithotripsy used to break up kidney stones, the researchers say.
In many cases of cancer, an entire tumor cannot be directly targeted by existing treatments due to its size, location, or even cancer progression.
According to the researchers, histotripsy has been shown to be valuable under less than optimal conditions.
Histotripsy is a promising option that will allow perhaps to overcome the limitations of current techniques and perform safe and effective noninvasive ablation of liver tumors, notes Tejaswi Worlikar, PhD student in biomedical engineering and one of the authors of the work.
“We hope that the data from this study will lead to preclinical and clinical trials of histotripsy, to create a treatment with histotripsy for people with of liver cancer.
— Tejaswi Worlikar
The Canadian Cancer Society estimates that approximately 3,300 Canadians were diagnosed with liver cancer in 2021 and 1,600 Canadians died from it.< /p>