Tumors Partially Destroyed with Sound Don’t Come Back

Noninvasive sound technology developed at the University of Michigan (U-M) breaks down liver tumors in rats, kills cancer cells and spurs the immune system to prevent further spread—an advance that could lead to improved cancer outcomes in humans. By destroying only 50% to 75% of liver tumor volume, the rats’ immune systems were able to clear away the rest, with no evidence of recurrence or metastases in more than 80% of animals.

The 700kHz, 260-element histotripsy ultrasound array transducer used in Prof. Xu’s lab

Even if we don’t target the entire tumor, we can still cause the tumor to regress and also reduce the risk of future metastasis,” said Zhen Xu, professor of biomedical engineering at U-M and corresponding author of the study in Cancers. Results also showed the treatment stimulated the rats’ immune responses, possibly contributing to the eventual regression of the untargeted portion of the tumor and preventing further spread of the cancer.

The treatment, called histotripsy, noninvasively focuses ultrasound waves to mechanically destroy target tissue with millimeter precision. The relatively new technique is currently being used in a human liver cancer trial in the United States and Europe. In many clinical situations, the entirety of a cancerous tumor cannot be targeted directly in treatments for reasons that include the mass’ size, location or stage. To investigate the effects of partially destroying tumors with sound, this latest study targeted only a portion of each mass, leaving behind a viable intact tumor. It also allowed the team, including researchers at Michigan Medicine and the Ann Arbor VA Hospital, to show the approach’s effectiveness under less than optimal conditions.

Histotripsy is a promising option that can overcome the limitations of currently available ablation modalities and provide safe and effective noninvasive liver tumor ablation,” said Tejaswi Worlikar, a doctoral student in biomedical engineering. “We hope that our learnings from this study will motivate future preclinical and clinical histotripsy investigations toward the ultimate goal of clinical adoption of histotripsy treatment for liver cancer patients.”

Liver cancer ranks among the top 10 causes of cancer related deaths worldwide and in the U.S. Even with multiple treatment options, the prognosis remains poor with five-year survival rates less than 18% in the U.S. The high prevalence of tumor recurrence and metastasis after initial treatment highlights the clinical need for improving outcomes of liver cancer. Where a typical ultrasound uses sound waves to produce images of the body’s interior, U-M engineers have pioneered the use of those waves for treatment. And their technique works without the harmful side effects of current approaches such as radiation and chemotherapy.

Our transducer, designed and built at U-M, delivers high amplitude microsecond-length ultrasound pulses—acoustic cavitation—to focus on the tumor specifically to break it up,” Xu said. “Traditional ultrasound devices use lower amplitude pulses for imaging.”

Source: https://news.umich.edu/

Tiny Bubbles Destroy Tumours in Seven Minutes

Following her diagnosis with liver cancer last June, 68-year-old Sheila Riley braced herself for painful and gruelling treatmentsSurgery, chemotherapy, radio-therapy and even ablation — where heat is used to destroy tumours — are some of medicine’s most effective tools against cancer, but the potential side-effects can be hard to bear. In fact, Sheila was spared these thanks to a radical new form of therapy that uses tiny bubbles of gas to destroy tumours within minutes and doesn’t leave a mark on the body. She was one of the first patients in the UK to undergo histotripsy, where focused ultrasound waves are directed from outside the body to destroy tumours by generating thousands of exploding gas bubbles. So rapid is the procedure that her tumour was obliterated painlessly — in under seven minutes.

It was amazing,’ says the grandmother of eight, who had the treatment last August at St James’s University Hospital in Leeds. ‘I didn’t need any medication — not even painkillers afterwards,’ adds Sheila, who lives in Bradford with her partner Frank, 70. ‘I was able to go shopping the next day, and two days after my treatment I was out with friends. It didn’t even leave a mark on my skin.

It is now hoped the procedure can help those with tumours in other parts of the bodyHistotripsy was pioneered by researchers at the University of Michigan in the U.S. and relies on a process called cavitation — creating an empty space inside something solid — to eradicate cancer. First, a beam of ultrasound energy is directed through the skin to the tumour site. As the beam hits the targeted spot, it activates thousands of pockets of gas that occur naturally in tissue throughout the body, even tumours, as a result of the respiratory process. These tiny pockets of gas are usually dormant, but when blasted with the sound waves, they expand, vibrate and explode, forming a high-energy cloud of microbubbles in the tumour. As they rapidly expand and collapse, the bubbles break up surrounding cancerous tissue, liquifying it into a solution that then gets passed out of the body as waste.

Unlike existing treatments such as microwave ablation, where a heat-generating probe is used to ‘cook’ tumour cells, there is no heat that might damage surrounding healthy tissue, making cavitation potentially safer. This capacity for ultrasound to destroy tissue has been known about for years but was not previously adopted as a cancer treatment because it was too difficult to control the bubble clouds and avoid damaging healthy tissue.

However, the process has now been fine-tuned and the energy source can be better directed inside the tumour, avoiding the risk of nearby healthy tissue or organs being affected. An international trial is now under way looking at histotripsy for liver cancer. The chief investigator, Professor Tze Min Wah, a senior consultant interventional radiologist at St James’s University Hospital, believes cavitation could transform cancer treatment. ‘Rather than using heat, radiation or surgery to remove the tumour, the bubble cloud created by histotripsy is so powerful that it ruptures the tumour but doesn’t damage the tissue around it,’ she says.

Source: https://www.dailymail.co.uk/