The treatment reduced liver tumor volume by 50% to 75%, then the rats’ immune system cleared the rest, with no signs of recurrence or metastasis in more than 80% of the animalsnote the authors of the work published in the journal Cancer (New window) (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 metastasis formation.explains in a press release the biomedical engineer Zhen Xu, who has been developing the technique since 2001 with colleagues from the University of Michigan.

An ultrasonic array transducer.

Professor Zhen Xu and student Tejaswi Worlikar around an ultrasound array transducer.

Photo: Michigan Engineering/Marcin Szczepanski

The technique is called histotripsy. Histories means cloth in ancient Greek, and tripsis friction, or grinding.

Ultrasound has been used for decades in medicine in ultrasound scans that 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 eventually 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 around forty participants in order to verify its interest in treating liver cancer in humans.

ultrasonic pulses

Histotripsy allows the mechanical splitting of tissue structure using a number of short, high intensity sound pulses. Ultrasound focuses energy towards a target with millimeter precision, which means that there is no damage to the surrounding tissues.

Our transducer emits ultrasonic pulses […] called acoustic cavitations that bombard the tumor to break it upsays Pre 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, radiation therapy or chemotherapy.

The intensity of the ultrasounds used is hundreds of times greater than that of current ultrasounds. It resembles that of lithotripsy used to break up kidney stonessay the researchers.

Useful in specific cases

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 shown its value in less than optimal conditions.

Histotripsy is a promising option that may overcome the limitations of currently available techniques and provide safe and effective non-invasive ablation of liver tumors.notes Tejaswi Worlikar, doctoral 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, with the ultimate goal of creating a histotripsy treatment for people with liver cancer.

The Canadian Cancer Society estimates that approximately 3,300 Canadians were diagnosed with liver cancer in 2021 and 1,600 Canadians died from it.



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