How to kill hard-to-reach tumours?  Particle physics is on the case.

How to kill hard-to-reach tumours? Particle physics is on the case.

CERN, a physics research center outside of Geneva, Switzerland, is best known for discovering some of the building blocks of our universe. But scientists there are also studying new ways to treat cancer. While current radiation therapies use beams of protons, charged particles called ions, or photons of light to kill cancer cells, another particle might be better suited to target tumors deep inside the body: the electron.

In a recent study, a team of physicists found that very high energy electron beams (VHEE) can reach tumors 10 times deeper than current treatments and with such precision that doctors may be able to target cancers near vital organs without damaging surrounding tissues.

Research at CLEAR (CERN’s Linear Electron Accelerator for Research), home to a 130-foot particle accelerator, has revealed that high-energy beams of electrons focused with magnetic lenses can penetrate deep into a “ghost of water” – a large bucket of water used for radiation studies—without scattering. The ghost is considered a suitable substitute for a human because the body has a high water content. The experiment could pave the way for future smaller linear accelerators – the type of particle accelerator used to generate VHEE beams – to be installed in medical facilities.

The results were “a big step towards a very simple idea”, says Dino Jaroszynski, a physicist at the University of Strathclyde and co-author of the research. “The main advantage of our method is that we can concentrate the dose in a small region. And it doesn’t happen anywhere else. »

The crucial next step for CLEAR, which does not conduct human trials, is to adapt the method for use in hospitals where the treatment can be studied in patients. Through a multimillion-dollar program at Lausanne University Hospital, located about 40 miles from CERN, clinical trials are expected to begin in 2025. CERN and Lausanne Hospital recently announced a partnership with a company called THERYQ which will manufacture linear accelerators for testing similar in size to MRI scanners.

The plan is to deliver VHEE beams to deep tumors in a fraction of a second using a technique developed in 2014 known as FLASH. “If you compress all the delivery doses in one treatment and in less than a second, you maintain the same effect on the tumor”, explains Roberto Corsini, principal investigator at CERN.

Using this approach with VHEE could lead to a “therapeutic revolution” in cancer care by allowing a radiation therapy program, typically administered over multiple sessions, to be delivered in one rapid swoop, Corsini says. The method could also target “tumors that can no longer be treated with radiotherapy because they are too close to a sensitive organ or are radio-resistant, so the dose would have to be increased to a level which would then be detrimental to the other tissue. “.

Cancer research in a physics lab

Low noise from vents and water pumps fills the windowless CLEAR facility, where the linear accelerator machinery rests on thick yellow-painted metal legs. Research at CLEAR began in 2017 and today around a quarter of the work there is investigating ways to use electron beams to treat medical conditions. While low-energy electron beams have been used to kill cancer cells in superficial lesions or damaged tissue near the surface of the body, beams with 5 to 20 times more energy could provide a lifeline. for patients with tumors that hide up to eight inches below the body. skin.

Cancer kills around 10 million people a year. About two million people will be diagnosed with cancer in the United States this year, and about half of that number will receive radiation therapy. A third of cancers are resistant to conventional radiation and chemotherapy drugs, which are unable to target individual tumours.

Current particle-based treatments come in several forms tailored to the nature of cancer cells. They include proton therapy, a precise treatment used to target cancers in parts of the body where damaged healthy tissue could seriously harm the patient, such as in the brain and neck. Ion therapy uses charged particle beams in high doses against treatment-resistant tumors, such as those of the throat, pancreas or liver. Photon beam treatments, on the other hand, emit radiation similar to that released during an X-ray, which is an effective way to kill cancer cells but carries the risk of collateral damage.

Some research has focused on whether deep-seated tumors can be treated with a combination of FLASH and proton therapy, but the machines to deliver VHEE are “planned to be much more compact and less expensive,” says Jean Bourhis, oncologist at the University of Lausanne. Hospital leading the human trial.

Despite the promising research, “much more needs to be done,” says Jaroszynski. Developing a new type of radiotherapy “requires years and years and years of testing just to prove that it works on the one hand, and also that it doesn’t have any unwanted side effects.” Researchers also have “many unanswered questions” about VHEE treatments, such as the most effective beam angle and radiation dose. Once the analysis is done, “we can optimize the beam parameters much better to really target and maximize effect and benefit.”

Still, scientists are optimistic that a new era of cancer treatment is on the horizon. For researchers at CERN, where a particle called the Higgs boson that interacts with other particles to create mass has been discovered, it’s an exciting new kind of physics.

“The Higgs boson is one thing,” says Mike Lamont, director of accelerators and technology at CERN. “Human beings are another. And that’s something we’re very happy to be a part of.

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