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.