Scalpels made of sound waves

Clinical Brief – August 11th

The Brief

We started with scalpels of steel. Now, surgeries often use heat to burn through flesh.

Could ultrasound be next?

Does it work?

A recently published study looked at hospital records of 150 men who had high-intensity focused ultrasound surgery for metastatic prostate cancer.

After three years, it was estimated that 40% of patients would be alive without treatment failure and/or signs of cancer and/or receiving systemic therapy (it’s a messy endpoint).

This by itself wasn’t very exciting. But when patients were broken down by risk groups, the data showed that patients with low-risk disease may see better results than those who had high-risk disease. The 40% stat you see above turned into 100% for low-risk patients; 49% for intermediate-risk patients; and 24% for high-risk patients.

The main reason why we’d use ultrasound for surgery though, provided that it works, is that we don’t need to actually cut anything. It works just like a regular ultrasound scan, except the sound waves used here is much more focused and high-frequency.

This wasn’t the first time that focused ultrasound was used to conduct surgery. Similar techniques have been used in brain surgery to treat essential tremor.

This trial came out towards the end of 2016, but it’s worth mentioning again because of how ultrasound was used.

Here, 76 patients who had treatment-resistant essential tremor was randomized to ultrasound or a sham procedure. The ultrasound was used to generate enough heat to burn off a tiny piece of brain tissue.

After the procedure, patients treated with ultrasound reported a 47% drop in hand tremors from before, compared to a 1% drop for the sham group.

Bottom Line

Focused ultrasound appears promising, and I can definitely see the merit behind surgery that doesn’t involve actual cutting. And as the essential tremor trial showed, ultrasound has the potential to be very precise and controllable – two features we’d need when it comes to surgeries.

That said, for prostate cancer at least, the study above highlighted the need for more research to figure out the right patient who’d benefit the most from this type of surgery.

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