It's a scary diagnosis. Of the 70,000 new brain tumors expected to be diagnosed in the American population next year, more than one-third will be malignant, meaning they're cancerous. And those tumors are difficult to remove because to a surgeon's naked eye, cancerous brain tissue looks like normal brain tissue. It's hard to differentiate and it's critical that doctors not harm healthy tissue during surgery.
"The problem is that everything in the brain is important and when we're taking out something like a tumor we don't want to hurt normal function that might be right next to them," said Dr. David Roberts, a neurosurgeon at Dartmouth-Hitchcock Medical Center in Lebanon, N.H.
So, Roberts and his colleagues are now on the forefront of more accurate brain tumor resections. Besides traditional preoperative MRI imaging as a guide, patients at Dartmouth now consume an oral drug before surgery. It makes cancerous cells fluoresce. Surgeons then use a microscope with a blue light, and remarkably, the cancer glows like lava.
"It was one of those wow moments," Roberts said. "No matter how many times you read about this or hear about it, when you actually see it under the microscope it is a very simple concept and it's a very striking phenomenon."
It certainly is. When you compare a portion of the brain under white light with no obvious signs of cancer to the same portion using fluorescence, the cancer shows as hot pink. The technique is improving accuracy tenfold, but it doesn't show smaller, low-grade brain tumors. And that's where a new probe comes in.
"Touch the brain, push a button and it glows through," said Kolbein Kolste of the Thayer School of Engineering.
Developed by doctors at Dartmouth and biomedical experts at its engineering school, the probe is now being studied at just a handful of research facilities nationwide.
"There are certain parts of the brain or tumors that don't glow as strongly and so we use this fiber optic probe to be able to detect the lower levels of light," Kolste said.
It's allowed doctors to use fluorescence technology on a much larger patient population-- those with high-grade, low-grade and deep-tissue tumors.
"This is a very powerful tool," Roberts said. "It won't cure these malignant tumors, but it will make the surgery that can help survival, it can help the quality of life and it will provide a tool to the surgeon to be able to do a much more accurate, safer job."
If approved by the FDA, Roberts believes these tools will become the standard of care in brain tumor removal. They've already made a difference for those participating in the clinical trials at Dartmouth.
Dartmouth researchers have been collaborating on the probe with the University of Toronto. Their work at detecting smaller, low-grade tumors with it is being funding by the National Institutes of Health.
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