A Better Way to Treat
Children With Cancer
Children undergoing a stem cell transplant to treat leukemia,
blood disorders or other types of cancer can safely undergo
a less toxic treatment regimen than one that is traditionally
used, report researchers from Columbia University Medical Center
and NewYork-Presbyterian Hospital in the journal Bone Marrow
Transplantation.
Typically, such patients have their
immune system destroyed with high doses of chemotherapy or
radiation before the transplant procedure. This allows the
transplanted stem cells to "take" and
start producing a new, healthy immune system.
However, the destruction of the
immune system leaves youngsters vulnerable to potentially
life-threatening infections and dangerously low white and
red-blood cell counts before the new immune system begins
functioning—a process that can take weeks or months.
And in the long run, the high-dose chemotherapy or radiation
may damage fertility, stunt growth and increase the risk of
a second, unrelated cancer later in life.
"Physicians would like to find a way to avoid the toxicity
of this treatment, known as myeloablation," said Dr. Mitchell
S. Cairo, professor of pediatrics, medicine and pathology at
Columbia University College of Physicians and Surgeons and
chief of the Division of Pediatric Hematology and Blood and
Marrow Transplantation at the Children's Hospital of New York-Presbyterian. "Some
of these children may die of infections in the first few weeks
after transplant, and if they do survive and the transplant
is a success, they can have problems further down the road."
"Leaving the immune system somewhat intact may help prevent
infections, particularly in those children who have relatively
few stem cells available for transplant," said Dr. Cairo.
In the new study, Dr. Cairo and colleagues tried a variety
of less toxic treatment regimens on a group of 21 children,
teens and young adults, all under the age of 21. The patients
had cancers or blood disorders of the immune system.
"We used what we call "reduced intensity" regimens
that used chemotherapy drugs, and in one case radiation, to
weaken the patient's own immune system," said Dr. Cairo. "This
has been tried in adults with some success, but there is little
data on this in children."
The children were then given transplants of stem cells collected
from the umbilical cord blood of unrelated donors or stem cells
from the bone marrow or blood of relatives. The children were
also treated with medication to prevent graft-versus-host disease
(GVHD), a potentially dangerous condition that occurs when
the transplanted cells attack the patient's tissue. GVHD can
cause a blistering rash, enlarged liver and intestinal problems
such as diarrhea.
The researchers found that 85 percent
or more of the children in the study achieved at least a
50 percent donor chimerism, meaning their immune system contained
a mixture of the patient's and the donor's cells. This is
a sign that the graft is "taking." In
about 24 percent of cases, the graft failed to take. "These
numbers are similar to those seen in adults undergoing a reduced
intensity regimen," said Dr. Cairo. "However, the
results should be interpreted with caution."
The study included children with
a wide variety of ailments, from leukemia and Hodgkin's disease
to an inherited blood disorder called beta-thalassemia. The
study participants had a variety of regimens using different
combinations of drugs. "Larger
studies are needed to look at how these results will vary depending
on a child's diagnosis and drug treatment," said Dr. Cairo. "And
a long-term follow-up is needed to determine their risk of
GVHD and side effects of treatment, such as growth stunting,
secondary cancers and infertility."#
