| Objective: To investigate the relationship between the biological features and the treatment efficacy and prognosis in acute myeloid leukemia subtype M2 (AML-M2) patients with chromosome 8 and 21 translocation.Methods: Bone marrow were obtained pretreatment from all patients and processed using unstimulated short-term (24-) cultures. G-banding was usually done. By using Kaplan-Meier analyses and Cox regression model, combining the clinical data, prognostic factors in 94 cases of de novo adult AML-M2 in our hospital from 2001 year to 2007 year were retrospectively analyzed.Result: The karyotype analysis did all pretreatment. Chromosome 8 and 21 translocation were identified in 53.2% (50/94) of AML-M2 cases, other than chromosome 8 and 21 translocation aberrations were 11.8% (13/94), left 33.0% (31/94) with normal karyotype.Among the 50 patients with t(8;21), 54% for 27 patients with sole t(8;21), Chromosome aberrations in addition to t(8;21) (q22;q22) were observed 46% for 23 patients. The most frequent secondary chromosome anomaly was loss of a sex chromosome (LOS), especially loss of the y-chromosome. The other secondary chromosome anomaly included-x, del9q,-x, dup(1q22-24),-y, +8,-9,-7,+ 4,+22,-8,del9q,del11q,del9del16. Partial patients (45cases) detected AML1/ETO fusion gene, 93.1% positive for 29 patients with t(8;21). But only 72 patients receivedchemotherapy. 49 patients got complete remission,left 23 patients fail to got complete remission.We compared the patients's average wbc,Hb,wbc index between the CR group and no CR group,found no difference,but the CR group had higher plt and low blast cell ratio of bone marrow .So the pretreatment plt and blast cell ratio of bone marrow are the important influencing factor on CR. In order to compared the effect of different additional aberrations on clinical outcome, we categorized these 72 patients into four groups: Group 1 (29cases) with normal karyotype; Group 2(12cases) with sole t(8;21); Group 3 (18cases) with other aberrations in addition to t(8;21); Group 4(13 cases) with other than chromosome 8 and 21 translocation aberrations. The patients′s average age,wbc,Hb,plt,blast cell ratio of bone marrow,wbc index had no difference among the four goups. The complete remission (CR) rates were 68.0% for all M2 patients, 86.2% for patients with normal karyotype, 82.3% for patients with sole t (8;21) and 33.3% for patients with additional chromosome abnormalities to t(8;21).〔(P<0.05 for t(8;21) additional chromosome abnormalities with sole t (8;21) and normal karyotype;P>0.05 for sole t (8;21) and normal karyotype〕.61.5% for patients with other than t(8;21) aberrations. The overall survival (OS) was 28.5 months for M2 patients with normal karyotype, 16.1 months for patients with sole t(8;21), 8.8 months for patients witht (8;21) additional chromosome abnormalities, 7.0 months for patients with other than t (8;21) aberrations〔P>0.05 for normal karyotype and sole t (8;21), P<0.05 for t(8;21) additional chromosome abnormalities with sole t (8;21) andnormal karyotype〕. WBC index=WBC×(% of marrow blasts/100). We distinguished the patients into 3 subgroups (low index, less than 2.5; intermediate index, 2.5~20; high index, 20 or more). The CR%:78.4%,66.7% and 60%, had no difference among the 3 subgroups, but the OS of the 3 subgroups was difference (P<0.05).The OS of the 3 subgroups were as follow: low index group 43.4month , intermediate index 12.7month , high index 16.1month. Multivariate analysis of prognostic factors showed that normal karyotype was the only influencing factor on OS .Conclusion: Cytogenetically, 53.2% cases had chromosome 8 and 21 translocation, 46% cases had t(8;21) with additional chromosomal abnormalities, and the main associated recurrent additional abnormalities were loss of a sex chromosome (LOS). The plt and blasts cell ratio in bone marrow have important influence on complete remission . AML with t(8;21) is not a single defined AML subset. t(8;21) AML-M2 patients with additional chromosome abnormalities had low complete remission rate,shorter survival time ,so it's a worse prognosis. The therapeutic effect of AML-M2 with sole t(8;21) and normal karyotype was considerable, considering the reasons maybe including limit cases,weaker possremission treatment and other unknown reasons. The wbc index have no influence on complete remission rate.But afferted the survival time.
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