Breakthrough: An ultrasound technique helps destroy liver cancer tumors without surgery

In a groundbreaking study, scientists at the University of Michigan used a device that emits focused, non-invasive ultrasound waves to destroy 75% of the volume of liver tumors in mice.

Then, the sound waves also stimulate the immune system, causing white blood cells to destroy the remaining 25% of the tumor. As a result, out of 10 mice treated in this way, 8 of them were completely cured, with no signs of metastasis and recurrence during the 3 months of follow-up.

Associate professor, Dr. Zhen Xu, who led the team at the University of Michigan and the cancer-fighting ultrasound transmitter they're developing.

The new treatment is called "histotripsy", with "histo" in Greek for "soft tissue", and "tripsy" for "decomposition". Histotripsy is the process of firing a focused beam of ultrasound, hundreds of times more intense than ultrasound imaging, at the tumor.

This focused ultrasound beam then contracts and explodes the air bubbles inside the tumor cells. This mechanical action breaks the walls of the cancer cells and gradually breaks down the solid tumor into a liquid form, so that the immune cells can clean up and eliminate them.

Unlike other cancer treatment technologies, histotripsy destroys tumors completely by mechanical action. It does not require surgery, does not generate heat, and does not ionize or irradiate cells.

"Histotripsy is a non-invasive, effective and promising option. It could overcome the limitations of current liver cancer treatments, such as surgical resection," said Tejaswi Worlikar, an engineer. biomedical sciences at the University of Michigan.

Sound waves explode air bubbles and thereby dissolve cancerous tumors.

Liver cancer is currently one of the top 10 killer cancers in the world. Even with multiple treatment options such as surgery, chemotherapy, radiation therapy, targeted drugs, and immunotherapy, the prognosis of liver cancer patients remains poor.

Only 18% of liver cancer patients in the US can live 5 years. The rate of tumor recurrence and metastasis after initial treatment is quite high. In addition, the liver is also a frequent site of metastatic tumors from the lung, breast, pancreas and rectum.

This poses a need for further development of new liver cancer therapies.

Histotripsy has previously been used in the treatment of calcified valvular stenosis and benign prostatic hyperplasia. However, the team that developed the technology at the University of Michigan now want to extend it to liver cancer.

They built an ultrasonic converging device, consisting of 260 transducers that broadcast at 700 kHz and an eight-probe device that generated sound waves at 1 MHz for animal testing.

The transmitters generate a focused beam of ultrasound waves that dissolve the tumor.

Two groups of mice, each with 11 mice, were transplanted with cancer cells to develop liver tumours. One group was treated with the histotripsy device, while the other group was left untreated as a control.

As a result, all 11 of the 11 untreated mice developed cancer to the metastatic stage. Meanwhile, 9/11 of mice treated with ultrasound, or 81%, showed signs of remission.

Associate professor Dr Zhen Xu, who led the research team at the University of Michigan, said: "Even if we don't target the entire tumor, we can still make the tumor regress and reduce the size of the tumor. risk of metastasis in the future".

The goal of treatment that Trend is aiming for is to destroy 50-75% of the original tumor, then let the immune system do the job of cleaning up the remaining tumor.

After about 10 weeks, the mice treated with histotripsy recovered from the disease. They also showed no signs of recurrence or metastasis until the end of the study.

Meanwhile, the untreated group of mice only lived an average of one and a half weeks. All of them died after 1-3 weeks because the tumor grew too large.

By 9/11 histotripsy-treated rats were in remission and did not relapse.

"This study demonstrates the potential of histotripsy technique for non-invasive tumor destruction and prevention of localized liver tumor progression and metastasis," the scientists said.

While previous trials with histotripsy have only shown the treatment to be effective in reducing tumor volume, this new study shows it also significantly increases survival rates.

"These results suggest that histotripsy may not increase the risk of developing post-resection metastases compared with controls. Future studies will continue to investigate safety, efficacy, and biological effects. of histotripsy," the researchers wrote.

"We hope that with what we have learned from this study, it will help advance future preclinical and histopathological trials, with the ultimate goal of applying histotripsy treatments to these patients." liver cancer patients".

Their study was published in the journal Cancers.

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