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Particle physics pushes the boundaries of cancer treatment

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Facility coordinator Roberto Corsini shows off a 40-metre linear particle accelerator at CERN that could push the boundaries of cancer treatment

Elodie LE MAOU

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Video by Elodie Le Maou

Researchers at the European science laboratory CERN, who regularly use particle physics to challenge our understanding of the universe, are also applying their expertise to push the boundaries of cancer treatment.

Physicists here are working with giant particle accelerators looking for ways to extend the reach of cancer radiation therapy and attack hard-to-reach tumors that would otherwise have been deadly.

In a CERN laboratory, called CLEAR, facility coordinator Roberto Corsini stands next to a large linear particle accelerator consisting of a 40-meter metal beam with tubes wrapped in aluminum foil at a extremity, and an extensive range of measuring instruments and protruding colored wires and cables.

The research here, he told AFP during a recent visit, aims to create beams of very high energy electrons – the negatively charged particles in the nucleus of an atom – which could eventually help fight cancer cells more effectively.

They are looking for “technology to accelerate electrons to the energies needed to treat deep tumors, which are greater than 100 million electron-volts” (MeV), Corsini explained.

The idea is to use these very high energy electrons (VHEE) in combination with a promising new processing method called FLASH.

This method consists of delivering the radiation dose in a few hundred milliseconds, instead of a few minutes as is currently the case.

This has been shown to have the same destructive effect on the targeted tumor, but cause far less damage to surrounding healthy tissue.

With traditional radiotherapy, “you create collateral damage,” said Benjamin Fisch, head of knowledge transfer at CERN.

CERN physicists want to extend the reach of cancer radiation therapy to hard-to-reach tumors that would otherwise prove deadly

Elodie LE MAOU

The effect of the brief but intense FLASH treatment, he told reporters, is to “reduce toxicity to healthy tissue while properly damaging cancer cells.”

FLASH was first used on patients in 2018, based on currently available medical linear accelerators, linacs, which deliver low-energy electron beams of around 6-10 MeV.

However, at such low energy, the beams cannot penetrate deeply, meaning the highly effective treatment has so far only been used on superficial tumors, found with skin cancer.

But CERN physicists are now collaborating with the Center hospitalier universitaire vaudois (CHUV) to build a FLASH delivery machine capable of accelerating electrons by 100 to 200 MeV, allowing the method to be used for much harder-to-reach tumors. .

Deep cancerous tumors that cannot be removed by surgery, chemotherapy or traditional radiotherapy are often considered a death sentence today.

“It is those who are not being cured at the moment who will be the targets,” Professor Jean Bourhis, head of the CHUV radiology department, told AFP.

Professor Jean Bourhis says the program, which will target deep cases, could be “a game-changer”.

Elodie LE MAOU

“For these particular cancers, which may account for a third of cancer cases, this could be a game-changer.”

It is hoped in particular that the FLASH method, with its much less harmful impact on the surrounding tissues, could make it possible to attack tumors lodged in the brain or near other vital organs.

Bourhis said it might not consign deaths from stubborn cancerous tumors to the history books, “but at least there will be a new opportunity for more cures, if it works.”

One of the challenges is to make the powerful accelerator compact enough to fit inside a hospital.

At CERN, a large gallery has been dedicated to housing the CLEAR accelerator, which requires 20 meters to push the electrons up to the required energy level – and an additional 20 meters to condition, measure and deliver the beam.

But Corsini insisted that CERN had the know-how to “speed up in a much more compact space”.

The prototype being designed with the CHUV will aim to do the same job with a machine that is 10 meters overall.

This “compact” solution, Corsini said, “cuts costs, reduces energy consumption and variability, and you can easily install it in a hospital without having to build an entire building.”

Construction of the prototype is expected to begin next February and clinical trials on patients could begin in 2025, Bourhis said, “if all goes well.”