Introduction 1 2 3 4 6 3 7 12 t 13 16 In the present study, we reviewed stained smears of blood and bone marrow from patients who were registered in the Japan Adult Leukemia Study Group (JALSG) AML-97 trial, and classified them into FAB subtypes and WHO categories. We also evaluated their survival on the basis of the WHO classification, the myeloperoxidase (MPO)-positivity of blasts, and cytogenetic findings including 11q23 abnormalities. Patients and methods Patients Between December 1997 and July 2001, 809 patients aged from 15 to 66 years with untreated AML (excluding M3) were registered from 103 institutions in the AML-97 trial of the JALSG. The patients were diagnosed with AML according to the FAB criteria at each institution. Patients with a history of MDS, hematological abnormalities before the diagnosis of AML, or a history of chemotherapy were not eligible for the AML-97 trial. Treatment strategies 17 17 Morphologic and cytochemical analyses 18 19 Cytogenetic analysis 3 t Statistical analysis P Results Patient characteristics 1 9 9 Table 1 Patient characteristics Age (year) 45 (15–66) Male/female 390/248 9 13.7 (0.4–709) Hemoglobin (g/dl) 8.3 (3.8–17.2) 9 52 (0–890) Bone marrow blasts (%) 56 (6–99) Values are presented as the median (range) WBC FAB classification 2 n n n Table 2 Number of patients according to the FAB classification Subtype Description No. of patients % M0 Minimally differentiated acute myeloid leukemia (AML) 30 4.7 M1 AML without maturation 109 17.1 M2 AML with maturation 261 40.9 M4 Acute myelomonocytic leukemia (AMMoL) 148 23.2 M4Eo AMMoL with eosinophils 23 3.6 M5a Acute monoblastic leukemia 19 3.0 M5b Acute monocytic leukemia 24 3.8 M6 Acute erythroleukemia 16 2.5 M7 Acute megakaryoblastic leukemia 5 0.8 Acute leukemia of ambiguous lineage 3 0.5 Total  638 100 WHO classification and clinical characteristics 3 1 P Table 3 Number of patients according to the WHO classification Category and subtype No. of patients % I. AML with recurrent genetic abnormalities 171 26.8    t 113 17.7 t 26 4.1    t – –    11q23(MLL)abnormalities 32 5.0 II. AML with multilineage dysplasia 133 20.8     Following MDS – –     Without antecedent MDS 133 20.8 III. AML and MDS, therapy-related – –      Alkylating agent-related – –      Topoisomerase type II inhibitor-related – –      Other types – – IV. AML not otherwise categorized 331 51.9      AML, minimally differentiated 25 3.9      AML without maturation 99 15.5      AML with maturation 108 16.9      Acute myelomonocytic leukemia (AMMoL) 63 9.9      AMMoL with eosinophilia 5 0.8      Acute monoblastic leukemia 8 1.3      Acute monocytic leukemia 16 2.5      Acute erythroid leukemia 6 0.9      Acute megakaryoblastic leukemia 1 0.2 Acute leukemia of ambiguous lineage 3 0.5 Total 638 100 Fig.1 Overall survival of patients categorized according to the WHO classification  4 9 9 Table 4 Comparison of clinical findings of patients diagnosed according to the WHO classification Category 9 9 Hb (g/dl ± SE) Age (year ± SE) Blasts in bone marrow (%±SE) MPO positivity of blasts (%±SE) I t a 1.4 ± 0.6 (113) 7.8 ± 0.2 (113) 41.6 ± 1.3 (113) 49.9 ± 2.0 (113) 93.3 ± 3.3 (108) inv(16) 57.8 ± 52.03 (26) 6.6 ± 1.2 (26) 9.2 ± 0.5 (26) 44.5 ± 2.6 (26) 50.5 ± 4.1 (26) 66.9 ± 6.7 (26) 11q23 38.3 ± 30.8 (32) 4.3 ± 1.1 (32) 8.9 ± 0.4 (32) 41.6 ± 2.4 (32) 56.3 ± 3.7 (32) 43.6 ± 6.1 (32) II  111.0 ± 121.5 (133) 3.0 ± 0.5 (133) 8.3 ± 0.2 (133) 44.2 ± 1.2 (133) 48.0 ± 1.8 (133) 34.0 ± 3.1 (126) IV  72.8 ± 91.7 (330) 5.1 ± 0.3 (331) 8.8 ± 0.1 (330) 43.8 ± 0.7 (331) 65.7 ± 1.2 (328) 53.7 ± 1.9 (312)   P P P P P P SE WBC MPO Hb a t 9 t 2 P Fig. 2 Overall survival of patients with high or low MPO-positive blasts  Cytogenetics n n n 5 3 P Table 5 Distribution of patients classified by cytogenetic risk Cytogenetic risk group No. of patients % Favorable 139 21.8 t 113 17.7  inv(16) 26 4.1 Intermediate 413 64.7  Normal karyotype 267 41.8  11q23 32 5.0  Ph(+) 7 1.1 t 4 0.6 t 4 0.6  Other 131 20.5 Adverse 54 8.5  Complex 41 6.4  −7 2 0.3  abn3 5 0.8  del5q 2 0.3  −5 1 0.2  Other 3 0.5 Total 638 100.0 Fig. 3 P  6 Table 6 Relationship between cytogenetic risk groups and MLD phenotype or MPO-positive rates of blasts  n n n Total MLD  + 0 129 (89.5%) 15 (10.4%) 144  − 138 (28.2%) 292 (59.6%) 38 (7.8%) 490  Unknown 1 2 1 4 MPO  High 123 (36.3%) 201 (59.3%) 15 (4.4%) 339  Low 11 (4.1%) 221 (82.5%) 36 (13.4%) 268  Unknown 5 23 3 31 High- and low-MPO indicates a percentage of myeloperoxidase positive blasts ≥50 or <50%, respectively MLD t t t t 4 t t P Fig. 4 P  7 t n n t P Table 7 t  No. of patients Auer MPO* MLD* FAB Median age (year) Median survival (day) + − High Low + − M1 M2 M4 M4Eo M5a** M5b t 9 0 9 1 8 0 9 0 0 3 0 6 0 39 1031.00 Other 11q23 23 5 18 13 10 10 13 1 3 13 1 2 3 48 520.00 Total 32 5 27 14 18 10 22 1 3 16 1 8 3 44.5 531.5 High- and low-MPO indicates a percentage of myeloperoxidase-positive blasts ≥50 or <50%, respectively MLD P P Discussion t t 20 22 21 23 24 25 P 18 26 26 t 19 18 19 3 7 12 20 22 3 n 3 n 7 8 t t t 15 27 30 t P 30 t t t 15 t 13 t t 30 t P 22 31 35 22 32 . 33 In summary, our results confirmed those of previous studies showing the prognostic significance of cytogenetics, MLD, and MPO-positivity of blasts in AML. Furthermore, we categorized patients with de novo AML according to the WHO classification and showed the clinical characteristics and OS of each category.