Cytogenetic Diagnostics and Outcome in a Series of Thirty Three Greek Pediatric Acute Myeloid Leukemia Patients

Acute myeloid leukemia (AML) accounting for approximately 17% of all childhood acute leukemias, arises either de novo or from a backround of myelodysplasia or previous chemotherapy. Cytogenetics is considered one of the most valuable prognostic determinants in AML while current risk–group classification in the limited cases of pediatric AML, is mainly based on cytogenetics and early treatment response. We reviewed the clinical and cytogenetic characteristics and the outcomes of 33 cases of childhood AML between 1997 and 2007 in order to investigate the incidence of the main FAB subtypes, the incidence of primary AML compared to secondary AML (s-AML) and the correlation between specific chromosome abnormalities and outcome in greek pediatric AML patients. Chromosome studies were performed on unstimulated bone marrow cells, derived from 33 pediatric AML patients, who were <18 years of age at the time of diagnosis. Eighteen patients were male and 15 were female. According to FAB classification one patient was classified as M0 (3%), 13 patients as M2 (39.4%), 4 as M3 (12.12%), 4 as M5 (12.12%), 2 as M6 (6.1%) and 4 as M7 (12.12%). No patient was classified as M4 while 5 patients with s-AML (15.15%) could not be classified. The median follow-up of all patients was 57.95 months (0.03–132.47). Overal survival and event free survival were 66,7% and 75,8% respectively. Eight patients with s-AML and 25 patients with primary AML were identified. The median age of patients with s-AML at diagnosis was 9.15 years while the median age of patients with primary AML was 7.2 years. Six out of 8 patients with s-AML died at a median follow up of 11.03 months. Nineteen out of 25 patients with primary AML are alive in complete remission (CR). Cytogenetic analysis was performed at diagnosis in 32 patients and results were obtained in 30 of them. The karyotype was abnormal in 21 out of 30 patients (70%). Normal karyotype was found in 9 patients, t(8;21)(q22;q22) in 5, t(15;17)(q22;q21) in 3, t(9;11)(p22;q23) in 3, −7/del(7q) in 5, del(9q) in 3, and complex karyotype in 4 patients. Three out of 4 patients with M3 are alive in CR with a median follow-up of 98.6 months while one with s-AML-M3 died 13 days post diagnosis. Three out of five patients with M2 and t(8;21), including 1 patient with s-AML, died at a median follow-up of 4.35 months. Three out of 5 patients with −7/del(7q) had s-AML and died in less than 4 years, while the two others are alive for more than 5 years, in CR. Although all patients with M7 had complex karyotypes, they are alive after a median follow-up of 96.73 months, 3 of them in CR and 1 in relapse. These results indicate that in greek patients, the main FAB subtypes show a distribution similar to that reported in the literature with the exception of M4 which is absent in our study but with a reported incidence of 20%. Pediatric patients with s-AML are older and their outcome is poor and is related to a higher probability of poor cytogenetic features compared to primary AML patients. Interestingly all patients with M7 had a good clinical course although they exhibited complex karyotypes.