Genetic markers pinpoint medulloblastoma as four diseases, not one

Medulloblastoma is the most common childhood brain cancer, and researchers have found genetic biomarkers that could separate it out into four different diseases and improve treatment selection and prediction of prognosis.

The researchers, from Stanford University School of Medicine and Lucile Packard Children's Hospital, took blood and tumor samples from 92 people with medulloblastoma, and compared the DNA. They found 12 frequent changes in single letters in the genetic code (known as point mutations), including some new mutations not seen before. These changes allowed the researchers to categorize the tumors into four types.

"We now understand that there are certain tumors with particular genetic signatures that are really resistant to standard treatments," said Yoon-Jae Cho of Stanford University School of Medicine, one of the authors.

Treatment of medulloblastoma, which affects up to 500 children in the U.S. each year, starts with surgery followed by radio- and chemotherapy. Despite improving the patient's outcome, the treatment can cause lasting physical or intellectual side effects. The assumption has been that medulloblastoma is one cancer, but this research shows that the tumors are not uniform. This genetic knowledge could eventually lead to less-toxic, better-targeted treatment approaches, and there are drugs in development that target two of the pathways affected by these mutations.

"Our plan is that within the next one to two years we will be able to offer kids a new set of compounds that have a clear biological rationale based on our genomic studies." Cho said. "We want to make sure we're being careful of what we move forward with, but at the same time, for some of these kids we don't have many, if any, effective and durable treatment options."

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