In a significant advance in the treatment of
acute childhood lymphoblastic leukemia (ALL), researchers from the
Pediatric Oncology Group have found that the use of drugs known to
cross into the central nervous system results in high survival rates
among the 10% of children whose cancer has relapsed and spread to the
brain and spinal fluid. This therapy will very likely become standard
treatment for ALL patients who experience this kind of relapse, said
the studys lead author, Dr. A. Kim Ritchey, of the Pediatric
Oncology Group in Chicago. This marks a significant advance in
the treatment of children whose disease has relapsed, he said.
High Survival Rate
In one of the largest studies of its kind, 83 children were treated,
prior to radiation therapy, with an intensive 6-month cycle of
chemotherapeutic drugs known to cross into the central nervous
system. The regimen consisted of weekly triple intrathecal therapy
with methotrexate, hydrocortisone, and cytarabine in age-adjusted
doses, as follows: age 1 and 2 years: methotrexate, 8 mg,
hydrocortisone, 8 mg, and cytarabine, 16 mg; age 2 to 3 years:
methotrexate, 10 mg, hydrocortisone, 10 mg, and cytarabine, 20 mg;
age 3 to 8 years: methotrexate, 12 mg, hydrocortisone, 12 mg, and
cytarabine, 24 mg; age ³ 9 years:
methotrexate, 15 mg, hydrocortisone, 15 mg, and cytarabine, 30 mg.
The strategy produced an overall survival rate of 71%, with patients
whose initial remission lasted 18 months or longer achieving a
survival rate of 83%.
To treat children enrolled in the study, we specifically picked
drugs that not only treated leukemia cells throughout the body, but
also got into the brain and spinal cordnot all chemotherapy
does, said Dr. Ritchey. After 6 months, the children received
radiation to the brain and spinal cord, followed by less intensive
chemotherapy for an additional 18 months. By delaying radiation, the
children were able to undergo more intensive chemotherapy than had
been used in the past, when radiation was given as soon as the
relapse was discovered.
Work is still needed to help children with more aggressive
disease, said Dr. Ritchey, noting that children who experienced
early relapse had a survival rate of only 46%.