August 30, 2006

Chemo for leukemia doesn’t harm brain development

NEW YORK (Reuters Health) - Unlike cranial radiation,
chemotherapy for children with a certain type of leukemia does
not appear to have harmful long-term effects on intelligence,
even at high doses, a new study shows.

Radiation to the brain had long been the standard treatment
for acute lymphoblastic leukemia (ALL). While this approach is
effective it can damage the brain, with particularly harmful
effects in young children, Dr. Brenda J. Spiegler of the
Hospital for Sick Children in Toronto and colleagues write in
the Journal of Clinical Oncology.

Treatment targeting the central nervous system (that is,
the brain and spinal cord) is essential for ALL patients, they
add, and therapies other than radiation, such as intravenous
methotrexate, are increasingly being used. But the effects of
these therapies on neurocognitive development are not clear,
Spiegler and her colleagues note.

To investigate, the researchers tested 79 patients
diagnosed with ALL between the ages of one and five years for
intelligence, academic achievement, attention and memory at an
average of 10 years after their diagnosis. All had received the
same basic chemotherapy regimen, while 25 also had cranial
radiation therapy, 32 were treated with high-dose methotrexate
in addition to standard chemo, and 22 received very high dose

Spiegler and her team found no difference in intelligence
and memory scores between the two methotrexate groups. These
patients scored close to the population average on 17 out of 18
measures of cognitive function. However, children who had
received radiation to the brain scored worse than the chemo
patients on most measures, and significantly lower than the
population average.

The degree of decrease in the scores of the radiation group
was important, the researchers report, "because children with
generalized deficits of this order often require special
accommodations to their academic programming."

Conversely, they conclude, treatment with methotrexate,
even at very high doses, appears to be "relatively benign" in
its effects on neurocognitive development and intelligence.

SOURCE: Journal of Clinical Oncology, August 20, 2006.