THURSDAY, Nov. 7 (HealthDay News) -- Recent decades have seen
huge strides in treating childhood cancer, but certain types of
tumors remain difficult to treat and are often deadly.
That's the frustrating fact at the heart of a meeting held this
week by the American Association for Cancer Research. Pediatric
cancer experts gathered in San Diego to discuss recent advances in
understanding childhood tumors and the obstacles to improving kids'
"The exciting thing is that we're in an era of unprecedented discovery," said Dr. John Maris, referring to recent research on the genetic underpinnings of childhood cancers. "But there's still a huge amount of work to be done."
One of the challenges in pediatric cancer research is that,
thankfully, it's relatively rare for children to develop cancer,
said Maris, who directs the Center for Childhood Cancer Research at
Children's Hospital of Philadelphia.
In the United States, one or two out of every 10,000 kids
develop cancer each year, according to the U.S. National Cancer
Institute. It amounts to around 12,000 cases of childhood cancer
and about 1,500 deaths annually.
Dr. James Downing, deputy director of St. Jude Children's
Research Hospital in Memphis, Tenn., said that's a very small
amount compared with the number of adults diagnosed with
As a result, Downing said, government funds and drug companies'
interests are largely focused on adult cancer.
"There are also very important practical considerations, because these are children," Maris said.
Drugs of any kind typically are tested first in adults to help
shield kids from toxic effects of experimental therapies. Safety
concerns, plus limited resources and other issues, can slow
"In pediatrics, we have to be very, very careful about prioritizing what we test," Maris said.
In some cancer areas, there have been huge success stories. A
major example is the blood cancer acute lymphoblastic leukemia
(ALL), the most common type of cancer in children. In the early
1960s, only about 4 percent of U.S. children diagnosed with ALL
were alive five years later. Now that number exceeds 90
Overall, the five-year survival rate from all childhood cancers
combined has risen from around 60 percent in the mid-1970s to more
than 80 percent in more recent years, according to the cancer
Downing said, however, that cancer still kills more kids under
age 15 than any other disease. And certain types remain stubbornly
resistant to everything doctors have thrown at them.
"There's a subset of cancers where we just have not made progress," Maris said.
One example is a tumor of the brain stem called pontine glioma
-- a "terrible disease," Downing said, that usually kills within a
Another example is neuroblastoma, a cancer of the nerve tissue
in various parts of the body that usually arises before age 5. Many
more kids survive the disease than in years past, but the chances
depend in part on the child's age.
Infants have a high cure rate, with about 90 percent alive five
years later; that dips to 68 percent among children diagnosed
between the ages of 1 and 4, according to the cancer institute.
The biology of a child's neuroblastoma is also key. "We used to
think all neuroblastomas were the same," Maris said. "They're
Maris and his colleagues found that mutations in a gene called
ALK are behind a rare form of neuroblastoma that runs in
An oral cancer drug -- already tested and approved for certain
cases of lung cancer in adults -- targets ALK. In early trials, the
drug, called crizotinib, led to remission in kids with the rare
form of neuroblastoma and children with an uncommon, aggressive
type of lymphoma.
At St. Jude, Downing and his colleagues have been working on a
project to "decode" the genomes of more than 600 children with
cancer in an attempt to gain a better understanding of the genetic
origins of various tumors. They've found specific gene mutations in
certain gliomas, neuroblastomas and rare subtypes of leukemia that
they hope will someday lead to better treatments.
But even with highly curable cancers, such as ALL, safer
treatments are needed. The chemotherapy, radiation and other
therapies used to battle kids' cancer can have unfortunate side
effects years later -- including other cancers and heart and lung
"When you're talking about children, a cure is not enough," Maris said.
Both Maris and Downing pointed to better funding as a vital
need. "We need advocacy at the legislative level to make sure
pediatric cancers aren't unwittingly discriminated against," Maris
Public support -- including donations to foundations supporting
pediatric cancer research -- can also help, Downing said. "This
can't get done without support from the general public," he
The National Cancer Institute has more on
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