Laser Therapy Opens New Possibilities for Treatment of Brain Cancer
Glioblastomas are the most common and aggressive form of brain cancer and one of the most difficult cancers to treat. Most patients diagnosed with this type of brain tumour survive just 15 months, according to the American Cancer Society. Glioblastomas are generally found in the cerebral hemispheres of the brain, but can be found anywhere in the brain or spinal cord.
Glioblastomas (GBM) are tumours that arise from astrocytes—the star-shaped cells that make up the “glue-like,” or supportive tissue of the brain. These tumours are usually highly malignant (cancerous) because the cells reproduce quickly and they are supported by a large network of blood vessels.
Glioblastoma is the most common primary malignant brain tumor; however, glioblastoma in children is less common than in adults, and little is known about its clinical outcome in children. Most children diagnosed with glioblastoma multiforme or anaplastic astrocytoma receive surgery and radiation, and in some cases chemotherapy.
There are many factors that affect that prognosis for a child with a glioma. The most important factor is the type of tumor. It is also very important if there were any tumor cells left after the tumor was removed. Some studies have shown that younger children have better prognosis than older children.
Overall the prognosis for pilocytic astrocytomas is very good; survival at 5 years is more than 90%. Unfortunately the prognosis for high-grade gliomas (anaplastic astrocytoma, glioblastoma multiforme and diffuse intrinsic pontine glioma) is poor despite aggressive surgery, radiation therapy and chemotherapy. The 5-year survival is less 15-35%. In a recent study, the 5-year survival was closer to 35% when at least 90% of the tumor was removed and was lower when less than 90% of the tumor was resected. In a recent study, the prognosis was also slightly better for patients with anaplastic astrocytoma (29% overall survival) than for children with glioblastoma multiforme (18% overall survival).
Washington University neurosurgeon Eric C. Leuthardt, MD, and others have discovered another benefit of laser surgery for patients with glioblastomas, one of the most difficult cancers to treat. In addition to killing the tumours with heat, the technology bypasses the brain’s protective cover to allow for up to six weeks of chemotherapy. Credit:Robert Boston
There is new hope on the horison however, thanks to a team of US researchers at Washington University School of Medicine in St. Louis.
The team found that a laser system already in place to kill brain tumours can also be used to disrupt temporarily the blood-brain barrier enabling the crucial chemotherapy drugs to pass into the brain for up to six weeks.
Laser heat is known to kill brain tumour cells, and was approved by the Food and Drug Administration (FDA) in 2009 as a surgical tool to treat brain tumours, but this is the first time it has been shown to disrupt the blood-brain barrier.
The Blood-Brain Barrier is a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, protecting the brain from toxins, but also blocking the passage of certain substances, including the delivery of chemotherapy drugs, limiting the treatment options for brain cancer.
Breaching the Blood-Brain Barrier has been attempted before, but previous attempts have had only limited benefits or have only been able to provide a window of about 24 hours, which is insufficient for consistent delivery of chemotherapy.
Using a laser probe, the team of neurosurgeons opened the brain’s protective cover, enabling them to deliver chemotherapy drugs to patients with a virulent form of brain cancer.
In a pilot study, 14 patients with glioblastoma – the most common and aggressive type of brain cancer – underwent minimally invasive laser surgery to treat a recurrence of their tumours. Heat from the laser is known to kill brain tumour cells but, unexpectedly, the researchers found that the technology can penetrate the blood-brain barrier.
“The laser treatment kept the blood-brain barrier open for four to six weeks, providing us with a therapeutic window of opportunity to deliver chemotherapy drugs to the patients,” said co-corresponding author Eric C. Leuthardt, MD, a Washington University professor of neurosurgery who treats patients at Barnes-Jewish Hospital.
“This is crucial because most chemotherapy drugs can’t get past the protective barrier, greatly limiting treatment options for patients with brain tumours.”
The study was published in the journal PLOS ONE on 24th February 2o16.
Combining laser ablation technology with a drug known as a PD-1 inhibitor that prevents tumour cells from evading the immune system could greatly enhance immunotherapy, Tran pointed out.
The temporary “window” raises the possibility that a host of chemotherapy drugs once rendered ineffective by the blood-brain barrier could now be used against glioblastoma — most common and deadliest malignant brain tumour in adults.
Researchers discovered that the blood-brain barrier opens soon after a procedure known as MRI-guided laser ablation – the laser beam creates the perfect temperature around the tumour — just warm enough to disrupt the blood-brain barrier but not so hot that neurons die.
The findings showed for the first time that the blood-brain barrier can be temporarily disrupted at tumour sites to provide a precise location and take a longer “window of opportunity” for chemotherapy drugs to enter the tumour and take effect. The laser only opens the barrier near the tumour, leaving the protective cover in other areas of the brain.
“This gives us a very significant window of time to give chemotherapy,” said David Tran, chief of neuro-oncology at University of Florida in the US.
Opening the blood-brain barrier also raises the possibility that immunological techniques can be used more effectively against brain tumours. A leaky barrier allows the tumour to be recognised more readily by the immune system and provides immune cells better access to the tumour.
Preliminary data suggests there could be a survival benefit to giving chemotherapy during the four to six-week opening in the blood-brain barrier, Tran noted.
“We are closely following patients in the trial,” said Leuthardt, who also is a Siteman Cancer Center member.
“Our early results indicate that the patients are doing much better on average, in terms of survival and clinical outcomes, than what we would expect. We are encouraged but very cautious because additional patients need to be evaluated before we can draw firm conclusions.”
Posted on 10 March, 2016, in Blog, Research and tagged blood-brain barrier, brain cancer, chemo, chemotherapy drugs, Chemotherapy Treatment, glioblastoma, laser treatment. Bookmark the permalink. Leave a comment.