Adult survivors of childhood Hodgkin disease have roughly four times the risk for stroke as their unaffected siblings, possibly due to radiation-related damage to the carotid artery or cardiac valves, according to an article published online September 20th by the Journal of Clinical Oncology.

“We were surprised. We knew there was increased risk of a second cancer ? usually breast cancer ? and increased risk of heart failure, but stroke was unexpected,” said Daniel Bowers, MD, principal investigator and lead author of the study.

Although doctors cure about 70 percent of pediatric outpatients with cancer, little research had linked strokes later in life to cancer. Testing that hypothesis on all survivors of childhood cancer was too impractical, the American research team narrowed the field to survivors of Hodgkin disease, the second most common form of childhood cancer.

“The goals are changing to more than just curing the child of cancer,” Bowers said. “They are to evaluate and reduce the long-term side effects. It’s been well-established that childhood cancer survivors have several well-described long-term side effects, including second cancers, learning problems, growth problems and heart damage.”

The National Institutes of Health-sponsored study involved 27 institutes and the statistical histories of some 20,000 childhood cancer survivors. From that database, researchers identified 1,926 people who had survived Hodgkin disease more than five years after being diagnosed between 1970 and 1986 and then identified 24 Hodgkin disease survivors who later reported a stroke.

When patient data were compared with that for their siblings, researchers found that only 9 of more than 3,800 siblings had suffered strokes. The incidence of strokes ? 83.6 per 100,000 person-years for Hodgkin disease survivors and 8.0 per 100,000 person-years for the control group ? demonstrated that Hodgkin disease survivors were at significantly increased risk for stroke.

The current research may support other studies suggesting the need to reduce the amount of radiation used in treatments for Hodgkin disease, Bowers said: “The next generation of studies will be able to look at the question: Does a reduction in radiation dose cause a decrease in the frequency of stroke? It certainly would be a logical expectation, but we don’t know that.”