Une sonde pour détecter le cancer du cerveau

Une sonde pour détecter le cancer du cerveau
Mise à jour le mercredi 11 février 2015 à 20 h 41 HNE

Des chercheurs montréalais ont mis au point une nouvelle méthode de détection du cancer qui pourrait améliorer le traitement des tumeurs au cerveau.

Un texte de Vincent MaisonneuveCourriel
Actuellement, « il est souvent impossible de distinguer visuellement les cellules cancéreuses des cellules normales dans le cerveau », indique le Dr Kevin Petrecca, chef du service de neurochirurgie à l'Institut et hôpital neurologiques de Montréal.
« D'où la persistance fréquente de cellules cancéreuses invasives après l'opération ainsi que la récurrence du cancer », ajoute le coauteur principal de l'étude publiée dans Science Translational Medicine.
Les chercheurs de l'Institut et hôpital neurologiques de Montréal, de l'Université McGill, du CUSM, et de Polytechnique Montréal ont conçu une sonde portative grâce à laquelle un chirurgien peut, durant l'opération, détecter en temps réel et avec beaucoup de précision les cellules cancéreuses. La sonde Raman a été testée sur 40 patients atteints de gliomes de grade 2, 3 et 4, des cancers très invasifs.
Professeur en génie physique à Polytechnique Montréal, Frédéric Leblond souligne que la précision de la sonde est supérieure à la technologie existante. L'appareil permet de repérer les cellules cancéreuses que ne détecte pas l'imagerie par résonance magnétique (IRM). En utilisant la sonde Raman, les chercheurs ont pu identifier des cellules cancéreuses situées à un centimètre de la tumeur détectée par l'IRM.
Les chercheurs estiment que la sonde Raman devrait améliorer la précision des interventions chirurgicales et ainsi prolonger la survie des patients. Pour démontrer l'efficacité de la technologie, l'Institut et hôpital neurologiques de Montréal mènera un essai clinique sur des personnes atteintes d'une tumeur au cerveau.


Blackburn News (Ontario)
Device could improve brain tumour surgery: study
By The Canadian Press on February 11, 2015 5:26pm

TORONTO - Canadian researchers have developed a fibre-optic probe they believe could help neurosurgeons track down stray cancer cells in patients with invasive brain tumours, thereby potentially reducing the risk of recurrence and improving life expectancy.
The hand-held device, called a Raman spectroscopy probe, was developed by researchers at McGill University for use by neurosurgeons in the removal of brain tumours called gliomas, which typically infiltrate healthy brain tissue.
The difficulty for surgeons is that current imaging technologies like MRI are unable to detect all the malignant cells that have seeded themselves within normal tissue outside the solid tumour, said Dr. Kevin Petrecca, the chief of neurosurgery at the Montreal Neurological Institute who helped design and test the probe.
"So being able to visualize the tumour in its entirety is one area we're unsuccessful at and the second one is that even if you could visualize the entirety of the tumour, it doesn't mean that you could remove all of those areas," Petrecca, who performs hundreds of brain tumour surgeries each year, said from Montreal.
"As a glioma surgeon, that's all I think about every day: I wish I could see those cells."
By using Raman spectroscopy — a technique that measures the way an object’s molecules scatter light — Petrecca said neurosurgeons can pinpoint cancer cells in small spots about a millimetre deep where the probe comes in contact with brain tissue.
In a study published Wednesday in Science Translational Medicine, the researchers showed the device detected not only the dense tumour mass, but also individual cancer cells that had penetrated surrounding tissue in 17 patients with advanced gliomas.
Since then, researchers have used the probe on a total of 40 patients without adverse effects. The team is planning a follow-up clinical trial that will assess whether use of the device increases patient survival.
Petrecca said the beauty of the probe is its simplicity: results from the probe are shown on a laptop within a second of it contacting the targeted area, allowing the surgeon to remove a tiny section of brain tissue if it is unlikely to cause physical or cognitive impairments in the patient.
Minimizing the amount of residual cancer left after surgery can affect survival, he said.
"The better resection you can do, the longer the patient lives. We're really talking about the difference of living six months versus three, four, five, six years. So it's a big, big deal."
There are different types of gliomas: some are more invasive and aggressive than others, usually strike at different points in life, and have varied life expectancies that range from months to decades, depending on the tumour type and at what stage it is diagnosed.
Petrecca believes that with further development, the Raman-based probe could become a valuable tool in the operating room, with a cost that's a tiny fraction of equipment like intraoperative MRIs and surgical robots.
"So do I think it's going to be transformational? Absolutely."
Dr. Mark Bernstein, a neurosurgeon at Toronto Western Hospital who specializes in brain tumours, called the Raman-based probe "an innovative application of sophisticated scientific theory and technology."
However, he said it would be impossible to identify every cancer cell. And even if it were possible, surgically chasing down all the cells could end up destroying vital brain tissue, potentially leaving the patient unable to speak, walk or see.
The tumour also might still recur because the genetic underpinnings that initially gave rise to the cancer still remain, said Bernstein, who was not involved in the research.
"I truly applaud the authors' idea and excellent and careful study of it, and await further data and advancement in techniques. But the chance of this technology translating into improved outcomes for patients with primary brain tumours is very low in my opinion," he said.
In fact, Bernstein believes that if a cure for these brain tumours is ever found, the solution won't be surgical but pharmaceutical, in the form of drugs that target the cancer cells at the molecular level while leaving healthy neurons unharmed.
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