Healthy Discoveries: Gene scan shows childhood brain cancer is different

Healthy discoveries

A study of the genetic map of brain tumors in children indicates they have many fewer mutations than alike tumors in adults -- meaning it may someday be easier to treat them, researchers reported.


The researchers reported in the journal Science that the study of medulloblastoma, the most public type of brain cancer in children, also turned up some new mutations.


"These analyses distinctly appear that genetic changes in pediatric cancers are remarkably unlike from adult tumors," Dr. Victor Velculescu of Johns Hopkins University in Baltimore, whose team led the study, said in a statement.

"With fewer modifications, the hope is that it may be easier to use the information to evolve new treatments for them." Medulloblastoma is the most common malignant brain tumor in children, diagnosed in about 400 children every year in the United States, with a survival rate of 70% and higher.


"It's a particular challenge to treat children with brain cancer as our most effective therapies, surgery and radiation therapy, can cause significant side impacts, including cognitive disabilities and hormone abnormalities," said Dr. Donald Parsons of the Baylor College of Medicine in Texas.

"For our youngest patients, the impacts can be potentially devastating." The researchers sequenced nearly all the genes in tumors taken from 22 children with medulloblastoma and compared them with ordinary DNA. Each tumor specimen had an average of 11 mutations, the researchers said, and they found 225 different mutations in all.


They compared these results to specimens from 66 other medulloblastoma tumors, including some specimens from adults.

They found some of the expected gene mutations. In 16% of the patients they found new and unexpected mutations in the MLL2 and MLL3 genes, genes known to help suppress tumors that were not before implicated in medulloblastoma.


"Like other genes found in medulloblastoma, the MLL2 and MLL3 genes disrupt normal brain development during childhood," Dr. Peter Phillips of The Children's Hospital of Philadelphia said in a statement.


"These genes interfere with biological signals during development."

The researchers said that targeted treatments that kill cells with known cancer-causing mutations are becoming more common in cancer handling and it may be potential to design drugs that can handle childhood brain tumors with fewer side impacts than current approaches.

"At the present, we must find out how to put the puzzle together and zero in on parts of the puzzle to develop new treatments," Dr. Bert Vogelstein of Johns Hopkins said in a statement. "This is what scientists will be concentrated on for the next decade."

The researchers said that they would also inquire whether mutations in other genes took part in development, such as the MLL genes, were involved in other types of childhood cancer.


The researchers said that they would also inquire whether mutations in other genes took part in development, such as the MLL genes, were involved in other types of childhood cancer.


Last week a team at St. Jude Children's Research Hospital in Memphis, Tennessee, and an international team of colleagues found that medulloblastomas could be divided into two unlike types of cancer, and suggested the youngest patients could receive less toxic therapies. 

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