"Researchers already know cancerous tumours often lack certain copies of genes. They also know certain cancer-promoting genes are mutated in cancer patients," says Joshua Schiffman, M.D., an HCI investigator. "But what's significant about this new research is that we've shown these two events occur simultaneously in a unique set of paediatric brain tumours - a finding previously unknown in these paediatric patients."
Schiffman, along with researchers from several other institutions including Stanford, Washington University, and UCSF, studied the tumours of paediatric brain cancer patients. Brain tumours are typically classified into grades 1-4 at the time of diagnosis based on their appearance under the microscope. Schiffman and colleagues studied samples from each brain tumour grade using new technology to detect either missing copies or extra copies of DNA. They also looked for mutations, or changes, in the DNA from the same brain tumour samples that can cause improper functioning of genes resulting in cancer. Researchers discovered genetic differences in the different tumour grades that may help explain tumour development and could lead to more accurate diagnosis and categorisation of patients. While more research is needed, Schiffman believes these findings can eventually lead to more targeted and individualised treatments.
The research focuses on BRAF, a gene known to be commonly affected in low-grade brain tumours called astrocytomas. Researchers studied more than 40 of these pediatric astrocytomas - the most common form of brain cancer in children - and found that five out of seven grade 2-4 astrocytomas with BRAF mutations occurred in combination with a deletion in CDKN2A, another gene associated with cancer. The findings suggest these combined alterations define a subset of paediatric malignant astrocytomas.
According to the Paediatric Brain Tumour Foundation, every day, nine children in the U.S. are diagnosed with a brain tumour. Brain tumours are the leading cause of cancer death from childhood cancer, accounting for 24 percent of cancer-related deaths. Paediatric brain tumours are different from those in adults and are often treated differently.
"A lot of progress has been made in our understanding of adult brain cancers, but we don't know as much about the genetics of paediatric brain cancers, which are the number one cancer killer of children," says Schiffman. "This information sheds new light in an area where little information was known. The ability to recognise unique subsets of tumours based on their genetic make-up could someday lead the way to more individualised treatments for paediatric brain cancers."
