2023-12-04 09:01:07
Powerful and hyper-precise, this radiotherapy technology is a weapon of mass destruction of tumors. All with minimal impact on the quality of life of patients… How does it work?
In May 2022, in the United States, a three-year-old English thoroughbred defied all odds by winning the prestigious Arkansas Derby, with a prize pool of $1.25 million. It was not so much the fact that an outsider won that made an impression as its name: CyberKnife. “Like the name of radiotherapy equipment”, Al Gold, its happy owner, told journalists that day. A retired real estate agent, this 60-year-old who is crazy about turf is a “cancer survivor”. Diagnosed and treated in 2020 for prostate cancer, in remission since, he added: “I owe this victory to this cutting-edge technology. » Giving his name to the star of his stable was his way of paying tribute to him. To hear him say it, the protocol seems to have been nothing more than a simple formality: “It took a few sessions, each lasting eighteen minutes, and it was done! » With remarkable power and precision, this machine, marketed by the Californian company Accuray, allows intervention on small tumors, whatever their location. And this while limiting as much as possible not only the side effects, but also the number of sessions and the total duration of treatment.
Followed since October 2017 at the Eugène-Marquis center in Rennes, for metastatic breast cancer, Karine, 48, was also amazed by the speed of the process: “In my case, it only took three sessions, which took place over three days in a row, last June. This involved treating a bone metastasis located in the lumbar region. Everything went very quickly… except for getting the prior MRI appointment! »
Five to ten times fewer radiation sessions!
In practice, in fact, everything starts with a medical imaging exam. This prerequisite allows doctors to set the number of sessions and the setting of the machine, to guarantee optimal effectiveness of the intervention. Then, a first session is planned, which serves to determine the position that the patient will have to adopt during the treatment1. This is also the time when personalized accessories can be made (casts of body parts or straps), sometimes useful, depending on the location of the tumor, to help the patient immobilize. Where, with conventional methods of radiotherapy, it generally takes 25 sessions spread over five to eight weeks, with this machine 2 to 5 sessions are enough. That’s five to ten times less! A feat made possible thanks to ultra-precise handling of so-called ionizing radiation (X-rays, gamma rays, radioactive rays), the power of which is used in all radiotherapy.
The basic principle of this technology is to “damage” the genetic material of the tumor cells. These are in fact much more sensitive to this treatment than healthy cells. This is what makes it possible to destroy some, while limiting the risk of damaging others. The radiation itself is not painful, so no anesthesia is needed. “On the other hand, it’s still quite impressivesays Karine. I had already been treated with conventional radiotherapy, but here we are faced with a gigantic machine, in a huge room. When, after helping me to settle in, the caregivers came out, and I found myself alone, lying on a kind of plate, with this arm going around me… I felt very small in this universe of high technology ! » The session generally lasts around thirty minutes, during which you should move as little as possible. The patient remains connected to the caregivers by a microphone. He can therefore, at any time, contact them and speak to them if he feels the need. If the patient has difficulty coping with feeling confined, or is subject to anxiety, it may be useful for them to talk about it in advance with the healthcare team, or with their doctor, or even with a psychologist, who will be able to advise them. relaxation techniques. And, of course, never hesitate to submit any questions that come to mind.
Submillimeter accuracy
“I was lucky enough to be comfortable enough with the team supervising me to ask them lots of questions. Everything was explained to me well”, testifies Isabelle. She received four sessions of radiation by CyberKnife at the Haut-Lévêque hospital, in Bordeaux, in 2019, for a metastasis located at the level of a vertebra. “I wasn’t worried. I even saw this arm as a bit like a friend, which I could almost touch, and which came to me to take care of me, with extreme precision. » How it works ? No less than 200 rays, generated by a powerful accelerator, converge towards the tumor. To reach their target, each takes a distinct path; as a result, healthy cells located on their trajectory receive a lower dose of radiation. Result: adverse effects, notably irritation and burns, are significantly reduced. Karine only reports one side effect: significant fatigue in the days, or even weeks, following the sessions. For even greater precision, the CyberKnife combines a robotic arm (comparable to those used in car manufacturing factories) with medical imaging guidance techniques. Its movements are thus controlled electronically, in accordance with the treatment plan defined before the intervention1.
IN NUMBERS
200 rays generated which all end up converging towards the tumor
2010 year of the arrival of CyberKnife in France
25 CiberKnife robots in France in January 2023
To detect tumor movements and patient movements with submillimeter accuracy and adapt to them, the tool relies on internal anatomical landmarks (bones, pulmonary opacities or implanted markers), monitored in real time using imagery. Any movement, even slight, linked for example to the patient’s breathing, is taken into account, for optimized targeting of only diseased cells. With this system, there is no need to trace or tattoo marks on the skin! Resulting from research begun at the end of the 1980s at Stanford University in the United States, this technology arrived in France at the beginning of the 2010s. It is used to treat tumors that are difficult to access by surgery, and whose location does not allow conventional radiotherapy to be carried out, for example the brain. It was for three brain metastases that Malika was treated, in February 2022, by CyberKnife. The operation having been considered too delicate, the patient’s doctor recommended three sessions. The Orléanaise had to go to Gustave Roussy to benefit from it. This is one of the few drawbacks linked to this cutting-edge machine: it is still far from being available everywhere. Only around twenty structures in France are currently equipped with them. “ And, where there is none, it is likely that this treatment will not be offered, underlines Malika. This is why you should not hesitate, if necessary, to seek a second opinion! »
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