Page 1124 - Hematology_ Basic Principles and Practice ( PDFDrive )

990 Part VII Hematologic Malignancies

1
0.9
0.8
0.7 62.8% ± 3.8% (2002−2008, n=203)
0.6
Probability 0.5 45.9% ± 4.1% (1991−2002, n=146)

0.4
0.3 22.4% ± 2.6% (1976−1991, n=255)

0.2
0.1
A 0
0 5 10 15 20 25 30 35 40
Years on study
1
0.9
0.8 72.3% ± 3.5% (2002−2008, n=203)
0.7 54.1% ± 4.1% (1991−2002, n=146)

0.6
Probability 0.5

0.4
0.3 29.4% ± 2.8% (1976−1991, n=255)

0.2
0.1
B 0
0 5 10 15 20 25 30 35 40
Years on study
Fig. 62.3 EVENT-FREE SURVIVAL (A) AND OVERALL SURVIVAL (B) FOR PATIENTS WITH
ACUTE MYELOID LEUKEMIA TREATED ON ST. JUDE TRIALS.

at the time of transplant, indicating that even though MRD is an are associated with risks of intracranial hemorrhage and respiratory
important predictor of posttransplant outcome, it is not a contrain- insufficiency secondary to leukostasis. Therefore, all patients with
dication to HSCT (Fig. 62.3). hyperleukocytosis, as well as those with symptoms of leukostasis
Children with Down syndrome and AML have a favorable prog- regardless of leukocyte count, should immediately receive interven-
nosis, with OS rates greater than 90%, and should be treated in tions to reduce the leukemic burden, such as leukapheresis, exchange
2
cooperative group trials that are designed to minimize toxicity while transfusion, hydroxyurea, or low-dose cytarabine (100–200 mg/m /
maintaining high cure rates. The excellent outcome has been at least day).
partly attributed to increased levels of cystathionine-β-synthetase, a Infectious complications are a major cause of morbidity and
high frequency of cystathionine-β-synthetase polymorphisms, and mortality in children with AML. In fact, the cumulative incidence of
decreased levels of cytidine deaminase in the blasts of patients with documented infection is greater than 60% among AML patients who
Down syndrome, all of which result in altered metabolism of cytara- do not receive prophylactic antibiotics. Randomized, controlled trials
bine. Approaches to the diagnosis, supportive care measures, and conducted in adults with AML demonstrated that prophylactic
treatment of childhood APL are similar to those in adults with APL, antibiotics, such as oral levofloxacin, are effective at reducing the
including the immediate initiation of all-trans retinoic acid (ATRA) incidence of bacterial infection, but similar studies have not yet been
followed by the continued use of ATRA and arsenic trioxide, with or completed in children. However, nonrandomized trials performed in
without the addition of conventional chemotherapy. pediatric patients with AML have shown that the use of prophylactic
antibiotics, such as cefepime alone or the combination of vancomycin
and ciprofloxacin, dramatically reduce the incidence of bacterial
SUPPORTIVE CARE infection and decrease the length of hospital stay compared with
historical controls. Although the emergence of drug-resistant bacteria
Supportive care is an essential component of the management of is a concern, we believe that the benefits of prophylactic antibiotics
children with AML. Initial leukocyte counts greater than 100,000/µL outweigh this potential risk (Box 62.2).