Cancer experts have released more than 500 genome sequences from children who have cancer, hoping that comparison of healthy and cancerous tissue from the same people will help solve the vexing mystery of how the various cancers develop.

The Pediatric Cancer Genome Project is a three-year, $65 million project to develop genome sequences of the major pediatric cancers. The latest list, of 520 different genome sequences, is published in the journal Nature Genetics. The genome sequences of samples from 260 young patients at St. Jude Children's Research Hospital.

The National Cancer Institute offers a "snapshot" of pediatric cancers. It notes that cancer is the leading cause of death by disease for American kids up to age 15 and estimates that 11,210 new cases of pediatric cancer are diagnosed in kids 0-14 each year.

Major childhood cancers include leukemias, which are blood cell cancers, and brain and other central nervous system tumors. Those combined make up about half of the cancers that affect children. White children develop cancer more often than children of other races, NCI said.

"We knew that if we only sequenced the tumor and not normal non-tumor DNA from the patient, we would end up with thousands to hundreds of thousands of potential mutations, and no way to sort through which ones were important to cancer," Dr. James Downing of St. Jude Children's Research Hospital told Time magazine. His hospital and Washington University teamed up for the pediatric cancer project.

"Ultimately, the researchers aim to use the genetic information to help develop new, more effective cancer treatments," wrote Alice Park in the Time article. "Despite the fact that survival rates of many childhood cancers has improved to reach 80 percent to 90 percent in recent years, much of this benefit is due to early detection and quick intervention with conventional treatment, including surgery, chemotherapy and radiation therapies. There have been no new drugs to treat pediatric cancers in nearly two decades and the rates of recurrent and new cancers among survivors remains high."

The project provided some background information, as well, hoping to make it easier for those working on treatments to translate the DNA information into a clinical weapon against cancer.

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