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Childhood Radiation Treatment Boosts 2nd Cancer Risk

Age and amount of radiation influences potential for secondary tumor, study finds

THURSDAY, Nov. 2, 2006 (HealthDay News) -- Children who received radiation for the treatment of cancer prior to 1986 run a higher risk of developing a brain tumor, a new study found. And the risk, though small, is influenced by a child's age at the time of treatment and the amount of radiation administered.

But, the overall risk of developing cancer in the brain remained small -- out of 14,361 youngsters who survived cancer, only 116 developed a subsequent brain tumor, the researchers said.

"The risk is small and seems to be concentrated to people who received radiation to the brain for the treatment of cancer," said the study's lead author, Dr. Joseph Neglia, a pediatric oncologist and researcher at the University of Minnesota Medical School and Cancer Center. "If you were a small child who received a large amount of radiation, then you have a higher risk and possibly should have a screening MRI."

What's most important for parents to know is that "treatment of the primary disease is still the most important thing. Even five years out from treatment, still the most common cause of death is recurrence of the primary cancer," Neglia said.

The study findings were published in the Nov. 1 issue of the Journal of the National Cancer Institute.

Data for the study came from the Childhood Cancer Survivor Study (CCSS), a large, retrospective study of children who have survived more than five years since their cancer treatment.

Neglia and his colleagues found that 116 individuals from the CCSS had developed a brain tumor that wasn't caused by their original cancer. To better assess where the risk came from, they matched each individual with brain cancer to four control subjects. They were matched by age, sex, and the time since the original cancer diagnosis.

The researchers found that radiation treatment increased the risk of developing a certain type of brain tumor called a glioma nearly sevenfold. And, the more radiation a child received, the more likely they were to develop brain cancer.

Additionally, age appeared to play a role. The risk of developing a glioma was highest in children who received radiation when they were younger than 5 years old, according to the study.

The researchers didn't find an increased risk of glioma from chemotherapy, said Neglia.

The children involved in this study all received treatment for their cancer prior to 1986. Neglia pointed out that cancer treatment has changed dramatically since then, so children treated today will likely face less risk in the future.

"We're less likely to use radiation and, when we do, we try to use lower doses," he said.

For those who received treatment in the past, it's important for them to know what treatment they received and to get appropriate follow-up care if they face an increased risk of developing a second cancer.

"This study confirms our concerns that the cost of curing cancer can be substantial," said Dr. William Carroll, director of the New York University Medical Center's Stephen D. Hassenfeld Children's Center for Cancer and Blood Disorders in New York City.

But, he added, "The incidence of second malignancy is still low compared to the overwhelming benefits of treatment."

"Forty years ago, many kids with cancer survived only days or weeks," Carroll said. "Today, the cure rate is 70 to 80 percent. The great majority of kids with cancer grow up to lead normal lives. But, once you're treated, you have an increased risk -- it's small, but it is increased -- of another malignancy, so you have to be more vigilant."

Carroll said that while it's important for everyone to avoid smoking, limit alcohol consumption, eat right and exercise regularly, it's even more important for people who've survived a childhood cancer. Additionally, if you've survived cancer in childhood, be sure you and your current doctor know what your diagnosis and treatment were at the time so you can be aware of any increased risks and get cancer screenings at the appropriate times.

More information

To learn more about childhood cancer, visit the Nemours Foundation.

SOURCES: Joseph Neglia, M.D., pediatric oncologist and researcher, University of Minnesota Medical School and Cancer Center, Minneapolis; William Carroll, M.D., director, New York University Medical Center Stephen D. Hassenfeld Children's Center for Cancer and Blood Disorders, deputy director of the New York University School of Medicine Cancer Institute, and the Julie and Edward J. Minskoff professor of pediatrics, New York University School of Medicine; Nov. 1, 2006, Journal of the National Cancer Institute
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