Survivors of childhood leukemia and brain tumors have an increased risk of
stroke later in life, a study shows. This is particularly true for children
treated with radiation therapy to the head at doses greater than 30 Gy.
These findings
justify the continuation of efforts to reduce radiation doses in children being
treated for leukemia or brain tumors when possible, conclude Dr. Daniel C.
Bowers from The University of Texas Southwestern Medical School, Dallas, and
colleagues.
The study, which was
published in the Journal of Clinical Oncology, included 4,828 leukemia survivors
and 1,871 brain tumor survivors. These subjects, who were younger than 21 years
when they were diagnosed between 1970 and 1986, were compared with a group of
3,846 of their siblings.
This is the first
study, the authors point out, to look at the risk of late-occurring stroke among
childhood leukemia survivors and is “by far the largest study” to examine the
risk of stroke in childhood brain tumor survivors.
According to the
team, 37 leukemia survivors and 63 brain tumor survivors experienced a stroke 5
or more years after diagnosis.
Compared with the
sibling group, the leukemia survivors had 6.4-fold greater risk of stroke, and
the risk for brain tumor survivors was increased by 29.0-fold.
In children who
received radiotherapy at an average dose of 30 Gy or greater had a stroke risk
that increased in a dose-dependent fashion.
“Importantly,
although the risk of stroke among leukemia and brain tumor survivors is
significantly increased, it is still a relatively uncommon event during the
first two decades after the cancer diagnosis,” the authors note.
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The rate of
late-occurring stroke for leukemia survivors was 57.9 per 100,000 per year, and
267.6 per 100,000 per year for brain tumor survivors.
“How this risk will change as these cancer survivors age is not known,”
the study team points out.
