Researchers in Philadelphia have localized the genetic variations that cause a common and often fatal form of childhood cancer, neuroblastoma, according to a study published Wednesday.
They found that the presence of common DNA variations in a region of chromosome six increased the risk of a person developing the most aggressive form of the cancer, the study in the New England Journal of Medicine said.
Neuroblastoma is a cancer of the peripheral nervous system that usually appears as a solid tumor in the chest or abdomen. It accounts for seven percent of all childhood cancers but causes 15 percent of all childhood cancer deaths.
"Until now we had very few clues as to what causes neuroblastoma," said lead study author John Maris, a pediatric oncologist at the Children's Hospital of Philadelphia in the state of Pennsylvania.
"Although there is much work to be done, understanding this cancer's origin provides a starting point for developing novel treatments."
Sometimes the cancer disappears spontaneously with minimal treatment, but when it appears in older children, it can be aggressive from the start.
In about half of cases, neuroblastoma is not discovered until after the tumor has spread throughout the patient's body.
Researchers at the Children's Hospital have been analyzing tumors and their variations for decades, and have been able to classify neuroblastoma according to the level of risk, to determine the most appropriate treatment.
But they know little about why children are predisposed to the disease.
In the latest study, Maris and Hakon Hakonarson, director of the hospital's Center for Applied Genomics, analyzed blood samples of about 1,000 neuroblastoma patients and 2,000 healthy children.
Genetic tests revealed three changes in the DNA helix, known as single nucleotide polymorphisms (SNPs), that were much more common in the cancer patients than in the healthy children.
"We are doing further studies to understand how these relatively common genetic changes translate into increased risk of cancer," Maris said.
"Ultimately, they probably cause subtle changes in gene expression during early development, interacting with other genes yet to be discovered. This suggests that neuroblastoma has complex causes."