Recently, Dr. Gelareh Zadeh, a neurosurgeon at Toronto Western Hospital, was operating on a 28-year-old patient with a brain tumour when a problem arose. After stimulating the brain area around the tumour, and asking the patient, who was awake, to follow certain commands, she realized the tumour involved the area of the brain that controls leg and foot movement.
Typically, a surgeon in this case has two choices. The first is to remove the tumour as safely as possible with the goal of getting as much of the cancer as they can and prolonging the patient’s life. However, doing that could significantly impair mobility, says Dr. Zadeh, who’s also the Co-Director of the Krembil Brain Institute and the Wilkins Family Chair in Neurosurgical Brain Tumour Research.
The second option would be to leave some of the tumour in to preserve and spare the patient’s leg function. It’s a gamble though. If the tumour is fast-growing and aggressive, it could turn fatal if it’s not fully removed. “This is one of the biggest challenges we face as brain tumour surgeons – how to maximize safe resection to give the best outcome for cancer treatment while preserving neurological function at the same time,” says Dr. Zadeh.
This is a common issue many brain surgeons face and they often have to make these kinds of touch choices. Advances in molecular and genetic testing, though, may be able to help surgeons solve this problem, says Dr. Zadeh.
Over the last few years, Dr. Zadeh and her colleagues have developed a way to immediately see the rate of the tumour’s growth. Through a new, quick method for genetic testing, Dr. Zadeh can tell if a tumour is what’s called an IDH-mutant tumour, which is slow-growing, or an IDH-wild type, which is fast growing.
Dr. Zadeh and her colleagues have just completed a study where they looked at 80 preserved brain tumour specimens and 50 samples from real-time operations. Laboratory technicians looked for the presence of the IDH mutation in the tumours using a common test known as mass spectroscopy, which can be completed in less than an hour. Their results matched the more widely used molecular test, which takes, on average, 10 days after surgery to get results. With a real-time test, results were 99 per cent accurate in determining whether a tumour had the IDH mutation or not.
The patient Dr. Zadeh was operating on had an extremely slow-growing tumour, according to the real-time test, so she chose to leave some of the tumour behind to preserve their leg movement. The patient can now walk normally. “I anticipate he won’t need another surgery for several years,” she says.
Dr. Zadeh’s test is currently only available at Toronto Western Hospital for patients with glial brain tumours, but her hope is that it will one day be covered for patients Ontario-wide.
As important as this one gene discovery is, what’s more profound is that Dr. Zadeh is bringing personalized medicine to neuroscience. Personalized medicine, which involves testing someone’s genes to target more specific treatments based on their genetic makeup, has taken off in other areas of medicine, but has been slow to be realized in brain tumors.
One of the challenges is the invasive nature of brain tumor biopsy – you have to get through the skull to take a genetic test, while some tumours are in areas critical to neurological function. Blood tests, though, can help determine the genetic and molecular profile of a tumor, which will then eliminate the need for an invasive biopsy.
While Dr. Zadeh is currently testing the IDH mutation in brain tumours, the mass spectroscopy test she relies on could also be used to test other mutations. That means surgeons may eventually have access to a wide range of genetic information about numerous brain diseases. Surgeons will be able to make real-time decisions affecting a patient’s surgery and treatment.
If a surgeon knows immediately what the genetic profile of a tumour is, and has drugs to target those genes, the surgeon can analyze a tumour and target it with those drugs – all in the same operation. That means patients will be able to start treatment earlier, and avoid having to undergo two risky brain surgeries. Dr. Eric Chen, a medical oncologist at Princess Margaret Hospital, explains that by putting the drug right on the brain, “you reduce the side effects from chemotherapy and more importantly, we hope that the treatment will be more effective.”
Dr. Zadeh agrees. “Real-time genetic tests during brain tumour surgeries will not only give the surgeon more confidence about decisions that are made during surgery, it will also transform the role of the surgeon,” she says. They’ll not only perform an operation, they’ll also be able to deliver gene-targeted therapies right to the brain. “This will open up avenues to providing therapeutics right at the point of surgery.”
Advertising feature produced by Globe Content Studio. The Globe’s editorial department was not involved.