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Extramedullary myeloid tumors in children: the limited value of local treatment
R D Jenkin1, M Al-Shabanah, A Al-Nasser
1Section of Radiation Oncology, Department of Oncology, The King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
Insights
Extramedullary tumors (EMT) in children with acute myeloid leukemia (AML) are associated with younger age and specific genetic translocations. Local treatment of EMT did not significantly impact survival rates, suggesting a conservative approach to radiation therapy.
Area of Science:
- Pediatric Oncology
- Hematology
- Cancer Research
Background:
- Extramedullary tumors (EMT) are a known complication in pediatric acute myeloid leukemia (AML).
- Understanding the incidence, associated factors, and treatment impact of EMT is crucial for improving outcomes in pediatric AML.
- Previous studies have varied in their definitions of EMT, impacting reported incidence and outcomes.
Purpose of the Study:
- To determine the incidence of extramedullary tumors (EMT) in Saudi Arabian children diagnosed with acute myeloid leukemia (AML).
- To identify factors associated with the development of EMT in this pediatric population.
- To evaluate the impact of local treatment on local tumor control, complete remission (CR), and survival rates in pediatric AML patients with EMT.
Main Methods:
- A retrospective study of 100 children treated for AML between 1983 and 1997.
- EMT at diagnosis was defined excluding meningeal leukemia, hepatosplenomegaly, lymphadenopathy, gingival hypertrophy, and cutaneous infiltration.
- Analysis included patient demographics, genetic factors (t(8;21) translocation), clinical presentation, treatment modalities (including local radiation), and outcomes.
Main Results:
- Extramedullary tumors (EMT) were diagnosed in 18% of pediatric acute myeloid leukemia (AML) patients at 25 sites.
- Children with EMT were younger and more likely to have meningeal leukemia at diagnosis; the t(8;21) translocation was associated with higher EMT incidence.
- Complete remission (CR) and survival were significantly influenced by bone marrow transplantation and achieving CR, not by EMT presence or local radiation treatment.
Conclusions:
- Permanent local control of extramedullary tumors (EMT) was achieved in all pediatric acute myeloid leukemia (AML) patients who attained bone marrow complete remission (CR).
- Local radiation treatment of EMT sites did not significantly contribute to overall CR or survival rates.
- Radiation therapy for EMT should be reserved for cases with immediate threats to vision, renal function, or spinal cord compromise.
Purpose:
To determine the incidence of extramedullary tumors (EMT) in Saudi Arabian children with acute myeloid leukemia, the factors associated with these tumors and the impact of local treatment on local tumor control, complete remission and survival rates.
Patients And Methods:
One hundred children, median age 6 years, who received their primary treatment for acute myeloid leukemia at King Faisal Specialist Hospital and Research Center, from 1983 to 1997 were studied. EMT at diagnosis occurred in 18 (18%) patients at 25 sites. Meningeal leukemia, hepatosplenomegaly, lymph node enlargement, gingival hypertrophy, and cutaneous infiltration were not included in the definition of EMT. With these exclusions, children with EMT were younger than those without EMT (median age, 3.5 v. 7.5 years) and were more likely to have meningeal leukemia at diagnosis (33% v. 10%). The t(8;21) translocation was associated with a 47% EMT incidence compared with 23% without the translocation. Local radiation treatment was given to 16 of 25 (64%) EMT sites.
Results:
The overall 5-year survival rate for all patients was 28%, and this was not significantly influenced by the drug regimen used, meningeal leukemia at diagnosis, the presence of the (8;21) translocation, M4 and M5 morphology combined, or EMT at diagnosis. Significant differences were observed in the 5-year survival rates for patients who underwent allogeneic bone marrow transplantation (52%; N = 37) and those who attained complete remission (CR) but did not undergo transplantation (21%; N = 44) and those who did not achieve complete remission with initial therapy (5%; N = 19). Systemic and local EMT CR was achieved in 17 of 18 patients with EMT, including 12 patients who underwent radiation treatment and 5 of 6 of those who did not. Isolated relapse was not seen at an EMT site and was not noted at any later stage of the disease.
Conclusions:
Permanent local control at sites of EMT was achieved in all patients who attained a bone marrow CR, whether or not the site was irradiated. Local radiation treatment of an EMT site did not appear to contribute to overall CR and survival rates. The use of radiation treatment should be conservative and limited to patients in whom there is a real and immediate threat to vision or renal function or when the spinal cord is compromised.
