Particle physics pushes the limits of cancer treatment

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

Physicists here are working with giant particle accelerators looking for ways to expand the reach of cancer radiotherapy and treat elusive tumors that would otherwise have been fatal.

In a CERN laboratory called CLEAR, the facility’s coordinator, Roberto Corsini, stands next to a large linear particle accelerator consisting of a 40-meter metal beam with tubes packed in aluminum foil at one end, and a wide range of measuring instruments and colored cables that stand out. and wires

The research here, he told AFP during a recent visit, is aimed at creating very high-energy electron beams – the negatively charged particles in the nucleus of an atom – that could eventually help fight cancer cells more effectively.

They are investigating a “technology to accelerate electrons to the energies needed to treat deep tumors, which is above 100 million electron volts” (MeV), Corsini explained.

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

Reduce ‘collateral damage’

This method involves delivering the radiation dose in a few hundred milliseconds, rather than minutes as is the current approach.

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

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

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

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

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

But physicists at CERN are now collaborating with the University Hospital of Lausanne (CHUV) to build a machine for FLASH delivery that can accelerate electrons from 100 to 200 MeV, making it possible to use the method for tumors much more difficult to target. attain.

‘game changer’

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

“It is the ones that we do not cure at the moment that will be the targets,” Professor Jean Bourhis, head of the CHUV radiology department, told AFP.

“For those particular cancers, which can be a third of cancer cases, it could be a game changer.”

There are particular hopes that the FLASH method, with its far less damaging impact on surrounding tissue, might make it possible to go after tumors lodged in the brain or near other vital organs.

Bourhis said he may 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.”

‘Compact’

One challenge is making the powerful accelerator compact enough to fit inside a hospital.

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

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

The prototype being designed with CHUV will aim to do the same job with a total 10-meter machine.

This “compact” solution, Corsini said, “reduces cost, reduces energy consumption and variability, and you can easily fit it into a hospital without having to build an entire building.”

Construction of the prototype is scheduled to begin next February, and clinical trials with patients could begin as early as 2025, Bourhis said, “if all goes well.”

© 2022 AFP