Stories about: brain tumors

Not all brain tumors are made the same, and that’s important

medulloblastoma
(saeru/Flickr)

When you look at an apple, no matter what variety, on the surface you can be pretty sure it’s actually an apple. From there, you can make lots of assumptions about it, like how it will taste when you bite into it and what will happen if you plant the seeds in your yard.

With cancer, we can’t make those kinds of assumptions. While two tumors from the same location in two patients may look the same, doctors and researchers have come to recognize that their behavior and the mutations driving them can be radically different, as can their response to therapy.

With that recognition, physician/scientists like Scott Pomeroy, MD, PhD, the neurologist-in-chief at Boston Children’s Hospital, are taking a deeper look at the tumors they commonly see and asking whether what on the surface looks like one kind of tumor might actually be something completely different. Pomeroy in particular has applied this view to one of the biggest questions in pediatric cancer: Why do medulloblastomas, the most common malignant childhood brain tumor, behave so differently from child to child?

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Challenging the dogma on deadly brain stem gliomas

Nestled in the pons (the red area above), the area that controls breathing, DIPG tumors have been impossible to biopsy and analyze for therapeutic insights. Until now. (MEXT Integrated Database Project/Wikimedia Commons)

Brain tumors can be very difficult to treat, but at least we know what to do about them. For years, a mix of surgery, radiation and chemotherapy has been used to treat brain tumors like medulloblastoma.

These treatments are fairly successful, but for a rare, almost always fatal tumor called diffuse intrinsic pontine glioma (DIPG), we haven’t had any success—in fact, we haven’t known where to start.

The problem has to do with where DIPGs are located: nestled among the nerves in a portion of the brain stem, the pons, that controls critical functions like our breathing, blood pressure and heart rate.

“For 40 years, we lacked the neurosurgical techniques to biopsy DIPGs safely,” say Mark Kieran, MD, PhD, director of the Brain Tumor Program at Dana-Farber/Children’s Hospital Cancer Center (DF/CHCC). “In fact, one of the first lessons every oncologist is taught still is, ‘Don’t biopsy brain stem gliomas.’ The dogma was that the risk of severe or fatal damage was too great.” And because we couldn’t biopsy them, we couldn’t study them to learn what makes them tick.”

A lot can change in four decades. Techniques for operating on the brain have advanced considerably, as have the tools for probing tumors at the molecular level. So, looking to turn the dogma about DIPGs on its head, Kieran has launched a clinical trial that aims to use advanced surgical and diagnostic tools to target and individualize DIPG treatment.

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Unmasking brain tumors with gene therapy

Brain tumors like the diffuse, light gray one in this MRI do a remarkably good job of hiding from the immune system. A new treatment based on gene therapy could strip their camouflage away. (Filip Em/Wikimedia Commons)

If there’s anything that tumors are good at, it’s hiding themselves. Not from things like MRIs or CT scans, mind you, but from the immune system. Since a tumor grows from what were at one time normal, healthy cells it’s still “self,” still one of the tissues that makes you you.

“Tumor cells display very subtle differences that distinguish them from healthy cells, but by and large they look the same to your immune system,” says Mark Kieran, a pediatric neuro-oncologist at the Dana-Farber/Children’s Hospital Cancer Center and Children’s Hospital’s Vascular Biology Program. “The question is: How can we unmask tumors so that the immune system can do its job?”

Researchers have worked for years on cancer vaccines aimed at getting the immune system to wake up to the presence of a tumor and turn on it. With a Phase 1 safety trial , Kieran and his colleagues, including Children’s neurosurgical oncologist Lily Goumnerova, are evaluating a different strategy for patients with hard-to-treat brain tumors called malignant gliomas:  They’re giving the tumors a cold.

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A urine test for brain tumors?

A urine sample can tell you many things. It can reveal pregnancy, signal an infection or unmask drug use. Could it also tell you about brain tumors? Maybe.

Current image-based screening for brain tumors and other neurologic diseases is time-consuming, costly and poses some risk—especially for young children who must be sedated to hold still in the scanner. The ordeal is multiplied for children who have had brain surgery and need frequent checks for disease resurgence — especially if they don’t live close to pediatric neuroimaging facilities.

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Childhood brain cancer: Learning to divide and conquer

Molecular fingerprints for two of the six tumor subtypes (courtesy Pomeroy and Cho)

Diversity is good in populations of people, but when it comes to cancer, it’s bad news. In the case of medulloblastoma—the most common malignant brain cancer in children—tumor diversity has been one of the greatest barriers to designing effective treatments.

Now, in the largest genomic study of human medulloblastomas ever, Children’s researchers and their collaborators have subdivided the cancer into six different diseases—each with distinct molecular “fingerprints.” Knowledge of these tumor subtypes will improve neurologists’ ability to direct and individualize treatment. One subtype, carrying the worst prognosis, had never before been characterized.

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