Acute Myeloid Leukemia in Children

Published on 04/03/2015 by admin

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Chapter 25 Acute Myeloid Leukemia in Children

Michael C. Wei, Gary V. Dahl, Howard J. Weinstein

Table 25-1 2008 World Health Organization Classification of Acute Myeloid Leukemia

Acute myeloid leukemia with recurrent genetic abnormalities

Acute myeloid leukemia with t(8;21)(q22;q22); RUNX1-RUNX1T1 (formerly AML1-ETO)

Acute myeloid leukemia with inv(16)(p13.1q22) or t(16;16)(p13.1;q22); CBFB-MYH11

Acute promyelocytic leukemia with t(15;17)(q22;q12); PML-RARA

Acute myeloid leukemia with t(9;11)(p22;q23); MLLT3-MLL

Acute myeloid leukemia with t(6;9)(p23;q34); DEK-NUP214

Acute myeloid leukemia with inv(3)(q21q26.2) or t(3;3(q21;q26.2); RPN1-EVI1

Acute myeloid leukemia (megakaryoblastic) with t(1;22)(p13;q13); RBM15-MKL1

Acute myeloid leukemia with myelodysplasia-related changes

Therapy-related myeloid neoplasms

Acute myeloid leukemia, not otherwise specified

Acute myeloid leukemia, minimally differentiated

Acute myeloid leukemia without maturation

Acute myeloid leukemia with maturation

Acute myelomonocytic leukemia

Acute monoblastic/monocytic leukemia

Modified from Vardiman JW, Thiele J, Arber DA, et al: The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: Rationale and important changes, Blood 114:937, 2009.

Extramedullary Acute Myeloid Leukemia: Myeloid Sarcoma and Leukemia Cutis

The management of acute myeloid leukemia (AML) presenting with extramedullary disease, including myeloid sarcoma and leukemia cutis, is challenging. Diagnosis of myeloid sarcoma by biopsy is necessary if there are no other indications of leukemia. Diagnosis of leukemia cutis should always be through biopsy and not fine-needle aspiration, and samples need to be prepared for analysis by immunohistochemistry and cytogenetics/fluorescence in situ hybridization (FISH). Treatment should be with systemic chemotherapy based on risk stratification of the underlying disease cytogenetics and mutational profile. Radiation therapy as consolidation should be considered, especially if there is an incomplete response with chemotherapy alone and with careful evaluation of site and potential toxicities. Imaging of myeloid sarcoma sites by computed tomography (CT), positron emission tomography (PET), or magnetic resonance imaging (MRI) can be used to monitor response to treatment. There may be prognostic significance of extramedullary disease occurring at certain sites such as the orbit, but this should not influence choice of systemic therapy. The presence of leukemia cutis is a marker of aggressive disease. Isolated myeloid sarcoma or leukemia cutis relapse should be treated as a systemic relapse, because progression to systemic relapse is almost universal. Leukemia cutis as relapse after transplant is particularly difficult to treat. Total skin electron beam irradiation can be used and often achieves a transient response with cessation of new lesions and regression of old lesions, but recurrence or progression is typical. Caution must be used with concurrent chemotherapy that may induce a radiation recall reaction.

Table 25-2 Outcomes From Recent Cooperative Group Pediatric Acute Myeloid Leukemia Trials

BFM, Berlin-Frankfurt Muenster; CCG, Children’s Cancer Group; COG, Children’s Oncology Group; EFS, event-free survival; JCACSG, Japanese Childhood AML Cooperative Study Group; NOPHO, Nordic Society for Pediatric Hematology and Oncology; OS, overall survival; SE, standard error; SJCRH, St. Jude Children’s Research Hospital; UK MRC, United Kingdom Medical Research Council.

Role of Hematopoietic Stem Cell Transplantation in Pediatric Acute Myeloid Leukemia

Outcomes in pediatric acute myeloid leukemia (AML) show a benefit for allogeneic transplant in first remission for select patients, but the risk for treatment-related mortality with transplant must be weighed against the improved outcomes with chemotherapy alone because of sequential dose-intensive regimens. The choice of chemotherapy versus hematopoietic stem cell transplantation (HSCT) in first remission therefore depends on prognostic factors and the availability of a suitable donor. The authors recommend matched related or, if a sibling donor is unavailable, matched unrelated HSCT for patients with high-risk features, including monosomy 7, FLT3 internal tandem duplication mutation, and patients with refractory disease after two courses of induction. Allogeneic HSCT in first remission should also be considered for non–Down syndrome patients with French-American-British (FAB) M7 morphology given recent reports of poor outcomes with this subtype. Favorable-risk patients (i.e., Down syndrome M7, inv[16], t[15;17], t[8;21]) should be treated with chemotherapy alone. All other patients without high-risk features in first remission should be treated with consolidative chemotherapy alone, because multiple studies have shown equivalent outcomes compared to autologous or allogeneic transplant. For these patients without high-risk features, matched related or matched unrelated HSCT should be reserved for relapsed disease. An autologous transplant should be considered in second remission when there is no suitable allogeneic donor. Haploidentical transplants are still considered experimental but show promise as an alternative especially with a KIR mismatch.

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