Stroke risk increases in childhood cancer survivors

Survivors of childhood cancers who received therapeutic radiation to the head or neck have an increased risk of stroke later in life that requires vigilant surveillance and monitoring. This increased risk of stroke increases over time, according to a report by the Children's Oncology Group (COG).

"Since our treatments have improved over the years, we're now seeing children who are surviving these cancers and realizing that there are long-term effects," said Sonia Partap, MD, a coauthor of the report (Neurology. 2009;73[22]:1906-1913) and an instructor in neurology, pediatric neurology, and neuro-oncology at Stanford University, Stanford, California.

Acute radiation therapy has the potential to disrupt microcirculation in medium and large cerebral arteries years later, according to the report, leading to intimal fibrosis, foam cell accumulation, luminal narrowing, thrombus formation, and weakening of the vessel wall, setting the stage for stroke and other forms of cerebrovascular disease.

"We know that kids who have predisposition syndromes have an increased incidence of vascular events, and we believe that it's more so from the radiation dose and location itself," said Partap. Patients at higher risk are those who receive radiation around the circle of Willis, she said. "Tumors included in that area are optic gliomas or tumors that involve the pituitary."

In the CCSC, the cumulative incidence of stroke increased over time, and the incidence was higher with higher maximal doses of radiation therapy to the temporal lobe, hypothalamus, and circle of Willis.

"A patient who received radiation to the head, neck, or chest should have a thorough physical examination to assess carotid pulses and ausculation for bruits," said Partap. "If there is clinical suspicion for compromised flow, carotid ultrasound should be obtained. A yearly neurologic examination is recommended for all patients, and imaging should be obtained if indicated."

Specific recommendations, depending on the cancer and treatment regimen, can be found in the COG Long-Term Follow-Up Guidelines, which are available at http://www.survivorshipguidelines.org/.

The pediatrician's role in working with childhood cancer survivors is to help reduce the incidence of diabetes, hypertension, and hypercholestoremia and to prevent metabolic syndrome, according to Partap. "Emphasizing and promoting healthy life practices with diet and exercise can decrease secondary stroke risk. These practices, if set early in life, will carry on with the child through adulthood and reduce risk for all cerebrovascular events," she said.

As children age, pediatricians and parents need to educate them about their diagnoses "so that when they become adolescents and young adults and go out in the world, they know how to inform their future care providers on what their risk factors are," Partap said.