Prior cranial radiation therapy was the most significant predictor of recurrent stroke among the childhood cancer survivors – with the risk tripling from 11% among those who did not undergo cranial radiation to 33% among those who received 50 Gy after 10 years (hazard ratio 4.4; 95% CI: 1.4-13.7).

Hypertension (HR 1.9; 95% CI: 1.0-3.5) and older age at first-stroke (HR 6.4; 95% CI: 1.8-23 for age 40 vs age 0-17 years) were also associated with greater risk for recurrent stroke.

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It is unclear why cranial radiation increases stroke risk. However, the researchers hypothesized that high-dose radiation may cause blood vessels to constrict and cause blockages. Studies have shown that radiation therapy is associated with occlusion in the arteries located within or nearby the radiation field. The elevated risk of stroke in childhood cancer survivors also appears to persist and even increase decades after treatment, suggesting radiation may cause delayed arteriopathy.

These findings have significant implications for treatment protocols moving forward, according to the researchers. Based on the study results, the UCSF has updated its procedures to screen patients for blood vessel injury and stroke risk factors. However, this is not required nationally, even though signs of diseased blood vessels are visible on MRI.

“The radiologists are so focused on looking in the brain area where the tumor used to be that they’re not looking at the blood vessels,” said Heather Fullerton, MD, professor of neurology and founder of the UCSF Pediatric Stroke and Cerebrovascular Disease Center.

“We are at a point where more children are surviving cancer because of life-saving interventions,” said Dr. Mueller. “Now, we are facing long-term problems associated with these interventions.”

Equipped with this knowledge of stroke risk factors in childhood cancer survivors, clinicians can better screen and follow-up with these patients to provide more effective care.


  1. Fullerton HJ, Stratton K, Mueller S, Leisenring W et al. Recurrent stroke in childhood cancer survivors. Neurology. 2015;doi:http:/​/​dx.​doi.​org/​10.​1212/​WNL.​0000000000001951.