Comparison of hypoplastic myelodysplastic syndrome (MDS) with ...

Leukemia (2008) 22, 544–550 & 2008 Nature Publishing Group All rights reserved 0887-6924/08 $30.00 www.nature.com/leu

ORIGINAL ARTICLE Comparison of hypoplastic myelodysplastic syndrome (MDS) with normo-/hypercellular MDS by International Prognostic Scoring System, cytogenetic and genetic studies T-C Huang1, B-S Ko, J-L Tang1, C Hsu, C-Y Chen, W Tsay, S-Y Huang, M Yao, Y-C Chen, M-C Shen, C-H Wang and H-F Tien Division of Hemato-Oncology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan

The differences in clinical features and prognosis between hypoplastic myelodysplastic syndrome (h-MDS) and normo-/ hypercellular MDS (NH-MDS) remain unsettled. In this study, the characteristics of 37 h-MDS patients and 152 NH-MDS patients were compared. Peripheral-blood white blood cell counts and bone marrow blast percentage were lower in h-MDS patients than in NH-MDS patients (P ¼ 0.012 and 0.016, respectively). Refractory anemia (RA) was predominant (56.8%) in h-MDS, whereas RA with excess of blast (RAEB) was most common (44.7%) in NH-MDS. Chromosomal abnormalities 7/7q occurred less frequently in h-MDS patients than in NH-MDS patients (0 vs 18.3%, P ¼ 0.022). There was no significant difference in the prevalence of mutations of RAS, AML1, JAK2, PTPN11, FLT3/ITD, and hypermethylation of SOCS1 and SHP1 between these two groups. International Prognostic Scoring System (IPSS) was ideal for predicting prognoses in h-MDS patients (P ¼ 0.002). In low- or intermediate-1 (Int-1)-risk MDS patients, h-MDS patients had a superior survival than NH-MDS patients (P ¼ 0.01). In conclusion, distinct from NH-MDS, h-MDS patients have different patterns of hemogram, distribution of French–American–British subtypes, cytogenetic changes and prognoses. IPSS is applicable in h-MDS as in NH-MDS. In patients with low- or Int-1-risk MDS, h-MDS patients have a better prognosis than NH-MDS patients. Leukemia (2008) 22, 544–550; doi:10.1038/sj.leu.2405076; published online 20 December 2007 Keywords: MDS; cytogenetic; genetic; epigenetic; IPSS

Introduction Hypoplastic myelodysplastic syndrome (h-MDS) is characterized by decreased marrow cellularity, which could be wrongly categorized as aplastic anemia.1 Clinically, h-MDS shares similar manifestations with normo-/hypercellular myelodysplastic syndrome (NH-MDS), such as cytopenia, bone marrow dyspoiesis, clonal chromosome changes and the possibility of transformation to acute myeloid leukemia (AML). However, it remains controversial whether h-MDS is a distinct clinicopathologic entity that differs from NH-MDS in terms of pathogenesis, clinical features, classification, patterns of chromosome changes, response to treatment and prognosis.2 Meanwhile, differences in nature of the disease of myelodysplastic syndrome (MDS) between Western and Eastern people have been previously reported,3,4 but little is known about the h-MDS group. Correspondence: Professor H-F Tien, Division of Hemato-Oncology, Department of Internal Medicine, National Taiwan University Hospital, no. 7, Chung-Shan South Road, Taipei 100, Taiwan, ROC. E-mail: [email protected] 1 These authors contributed equally to this work. Received 15 August 2007; revised 23 October 2007; accepted 19 November 2007; published online 20 December 2007

Several hypotheses and models have been proposed for the pathogenesis of MDS, including flawed apoptosis,5 hypermethylation of tumor suppressor genes such as p15,6 and SOCS1 (suppressor of cytokine signaling-1),7 which results in gene silencing, unbalanced differentiation and proliferation of progenitor cells,8 and dysregulation of immune response.9 Mutations of a lot of genes including AML1,10 FLT311 and RAS12,13 are all introduced into the elaboration of MDS mechanism, but their changes in h-MDS remain elusive. As far as survival is concerned, International Prognostic Scoring System (IPSS) plays a decisive role in the prognosis prediction of patients with MDS,14 but its applicability to h-MDS is not confirmed. In this study, we sought to compare the clinical features, chromosomal abnormalities, genetic and epigenetic alterations between h-MDS and NH-MDS in a large cohort of Chinese patients in Taiwan, and to verify the applicability of IPSS in this special entity of MDS.

Materials and methods

Patients We retrospectively reviewed medical records and bone marrow findings in 189 patients with primary MDS diagnosed at the National Taiwan University Hospital, a tertiary referral hospital, between 1984 and 2002. The diagnosis and classification of MDS were made according to the French–American–British (FAB) criteria.15 Patients with chronic myelomonocytic leukemia or secondary MDS due to antecedent hematological diseases or drugs were not enrolled into our study. Most patients received supportive treatment only. Twenty-four patients were treated with low-dose cytosine arabinoside, 11 with conventional chemotherapy for AML and 18 received allogeneic hematopoietic stem cell transplantation. For Kaplan–Meier survival analysis, the closure date was 30 November 2006. Patients receiving hematopoietic stem cell transplantation were censored at the time of transplantation. This study was approved by the Institutional Review Board of the National Taiwan University Hospital.

Bone marrow aspiration and biopsy For the initial diagnosis, all patients received bone marrow aspiration and trephine biopsy. Bone marrow aspirate smears were routinely stained with the modified Wright–Giemsa stain (Liu stain),16 and biopsy specimens were stained with hematoxylin–eosin after decalcification. Hypoplasia was defined as less than 30% of the cellularity in the bone marrow biopsy specimen.17,18 The criteria for dyspoiesis included megaloblastoid changes, irregular-shaped nuclei or karyorrhexis of erythroblasts, micro-

Comparison of hypoplastic MDS with normo-/hypercellular MDS T-C Huang et al

megakaryocytes, hypolobated or binucleated megakaryocytes and pseudo-Pelger Huet anomaly or hypogranulation of granulocytes.19 Any of the aforementioned features should surpass 10% in the same lineage to be considered as the evident dyspoiesis.

Cytogenetics Chromosome study was performed in 175 of the 189 patients. Bone marrow cells were harvested directly or after 1–3 days of unstimulated culture as described previously.6 Metaphase chromosomes were banded by trypsin–Giemsa technique and karyotyped according to the International System for Human Cytogenetic Nomenclature.

Mutation analysis Gene mutation studies were performed in 103 patients (19 h-MDS and 84 NH-MDS) for AML1, RAS and JAK2; 102 patients (19 h-MDS and 83 NH-MDS) for PTPN11 and internal tandem duplication of FLT3 (FLT3-ITD); and 101 patients (18 h-MDS and 83 NH-MDS) for KIT. Mutations of AML1 were detected by genomic DNA PCR and direct sequencing using a Table 1

previously described method.20 The primer sets used to amplify exons 3–8 were the same as those designed by Harada et al.21 Abnormal sequencing results were confirmed by at least two repeated analyses. Point mutations at codons 12, 13 (exon 1) and 61 (exon 2) of the N-RAS and K-RAS genes were analyzed by PCR on genomic DNA and direct sequencing.20 Analysis of FLT3-ITD was performed as in previous studies.22,23 Mutations of JAK2 and PTPN11 genes, encoding Janus kinase 2 and Shp2, a non-receptor tyrosine phosphatase, respectively, were analyzed using reported methods.24 Mutations of KIT were detected by genomic DNA PCR and direct sequencing according to a previously described method.25 The methylation status of SOCS1 and SHP1 (Src homology domain 2-containing phosphatase-1), both encoding proteins functioning as negative regulators of signal transduction, was analyzed in 89 patients (17 h-MDS and 72 NH-MDS) and 87 patients (17 h-MDS and 70 NH-MDS), respectively, by methylation-specific PCR as previously described.26,27

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Statistics Mann–Whitney U-test was utilized to compare medians of age and hemogram parameters between h-MDS and NH-MDS

Comparison of clinical and laboratory features between hypoplastic and normo-/hypercellular MDS Total

Age (years), median (range) Gendera Female Male Hemogram, median (range) WBC ( 109 l1) ANC ( 109 l1) PLT ( 109 l1) Hb (g l1)

56 (1–88) 189 57 (30.2) 132 (69.8) 3.300 1.247 61 80

(0.440–40.500) (0.029–17.000) (2–607) (30–140)

Hypoplastic MDS 58 (26–86) 37 8 (21.6) 29 (78.4) 2.370 0.986 54 78

(1.000–15.700) (0.196–10.360) (3–433) (40–140)

Normo-/hypercellular MDS

P-value

55 (1–88)

0.967

152 49 (32.2) 103 (67.8)

0.207

3.520 1.426 67 80.5

(0.440–40.500) (0.029–17.000) (2–607) (30–130)

0.012 0.128 0.095 0.535

BM blast (%), median (range)

5.2 (0–29.6)

2.6 (0–26.0)

6.2 (0–29.6)

0.016

FAB classificationa RA RARS RAEB RAEB-T

189 62 15 77 35

(100) (32.8) (8.0) (40.7) (18.5)

37 21 2 9 5

(100) (56.8) (5.4) (24.3) (13.5)

152 41 13 68 30

(100) (27.0) (8.6) (44.7) (19.7)

0.007 0.001 0.739 0.023 0.483

IPSSa,b Low Intermediate-1 Intermediate-2 High

172 23 67 56 26

(100) (13.4) (39.0) (32.6) (15.0)

33 3 19 8 3

(100) (9.1) (57.6) (24.2) (9.1)

139 20 48 48 23

(100) (14.4) (34.5) (34.5) (16.6)

0.189 0.574 0.015 0.257 0.418

Treatmenta HSCT Anthra-based C/T Low-dose Ara-C

18 (9.5) 11 (5.8) 24 (12.7)

5 (13.5) 0 (0.0) 6 (16.2)

13 (8.6) 11 (7.2) 18 (11.8)

0.357 0.126 0.474

Acute transformationa

45 (24.1)

3 (8.1)

42 (28.0)

0.004

Survival, median (months) Low+intermediate-1 Intermediate-2+high

27 45 12

24 32 12

0.003 0.01 0.405

58 112 16

Abbreviations: ANC, absolute neutrophil count; Anthra, anthracycline; Ara-C, cytosine arabinoside; BM blast, bone marrow blast percentage; C/T, chemotherapy; FAB classification, French–American–British classification; Hb, hemoglobin level; HSCT, hematopoietic stem cell transplantation; IPSS, International Prognositic Scoring System; MDS, myelodysplastic syndrome; PLT, platelet count; RA, refractory anemia; RAEB, refractory anemia with excess of blast; RAEB-T, RAEB in transformation; RARS, refractory anemia with ringed sideroblast; WBC, white blood cell count. a Number of patients (%). b Only 172 patients, including 33 patients with hypoplastic-MDS and 139 patients with normo-/hypercellular-MDS, could be evaluated by IPSS. Leukemia


546 Table 2

Comparison of genetic alterations between hypoplastic and normo-/hypercellular MDS Total a

175 93 16 26 21 11 38 14 30

(53.1) (9.1) (14.9) (12.0) (6.3) (21.7) (8.0) (17.2)

33 19 1 0 4 2 8 3 3

11/103 13/103 2/103 3/102 2/102 0/101

(10.7) (12.6) (1.9) (2.9) (2.0) (0.0)

1/19 1/19 1/19 0/19 0/19 0/18

Karyotype Normal 5, 5q 7, 7q +8 20q Single aberration Double aberrations Complex aberrations Gene mutationb RAS mutation AML1 mutation JAK2 mutation PTPN11 mutation FLT3-ITD KIT Gene hypermethylationc SOCS1 SHP1

Hypoplastic MDS

38/89 (42.7) 54/87 (62.1)

(57.6) (3.0) (0.0) (12.1) (6.1) (24.2) (9.1) (9.1) (5.3) (5.3) (5.3) (0.0) (0.0) (0.0)

5/17 (29.4) 9/17 (52.9)

Normo/hypercellular MDS 142 74 (52.1) 15 (10.6) 26 (18.3) 17 (12.0) 9 (6.3) 30 (21.1) 11 (7.8) 27 (19.0) 10/84 12/84 1/84 3/83 2/83 0/83

P-value 0.580 0.279 0.022 0.678 0.677 0.630 0.657 0.275

(11.9) (14.3) (1.2) (3.6) (2.4) (0.0)

0.648 0.528 0.479 0.668 0.750 F

33/72 (45.8) 45/70 (64.3)

0.470 0.688

Abbreviations: AML1, acute myeloid leukemia 1; FLT3, FMS-like tyrosine kinase 3; ITD, internal tandem duplication; JAK2, Janus kinase 2; MDS, myelodysplastic syndrome; PTPN11, protein tyrosine phosphatase nonreceptor type 11; SHP1, SH2-containing protein tyrosine phosphatase 1; SOCS1, suppressor of cytokine signaling 1; 5, monosomy 5; 5q, 5q deletion; 7, monosomy 7; 7q, 7q deletion; 20q, 20q deletion; +8, trisomy 8. a Number of patients (% among patients who had cytogenetic study). b Number of patients with gene mutation/number studied (%). c Number of patients with gene hypermethylation/number studied (%).

patients. Pearson’s w2 test was utilized to detect the difference of gender, FAB classification and IPSS distribution between h-MDS and NH-MDS patients. Fisher’s exact test was utilized as required. A Cox proportional hazards model was used for multivariate regression analysis. Kaplan–Meier analysis with log-rank test was performed to evaluate the difference in acute leukemic transformation rate and survival between groups. All statistical analyses were performed by SPSS 13.0 for Windows (Chicago, IL, USA). P-values less than 0.05 are taken as statistically significant.

Results

Clinical and laboratory features Among 189 MDS patients, 37 (19.6%) patients were diagnosed as having h-MDS. Twenty-nine of them were males and eight were females. Males were predominant both in h-MDS and NH-MDS patients. Median ages of h-MDS and NH-MDS patients were 58 and 55 years, respectively (Table 1). Compared to NH-MDS patients, peripheral-blood white blood cell count and marrow blast percentage were significantly lower in h-MDS patients (P ¼ 0.012 and 0.016, respectively). There was no significant difference in platelet count and hemoglobin level between h-MDS and NH-MDS patients (Table 1). Refractory anemia (RA) predominated in h-MDS patients, whereas RA with excess of blast was the most common subtype in NH-MDS patients. The distribution of FAB subtypes in h-MDS was significantly different from that in NH-MDS (P ¼ 0.007) (Table 1). Among 33 h-MDS patients who had cytogenetic analysis, 14 (42.4%) had clonal chromosomal abnormalities, an incidence similar to that of NH-MDS patients (Table 2). None had monosomy 7 (7) or 7q deletion (7q), compared with Leukemia

26 (18.3%) of the NH-MDS patients (P ¼ 0.022). No significant difference in other cytogenetic changes was noted between h-MDS and NH-MDS. On the basis of IPSS, 3 h-MDS patients were risk-categorized as ‘low’, 19 patients as ‘intermediate-1 (Int-1)’, 8 patients as ‘intermediate-2 (Int-2)’ and 3 patients as ‘high’ (Table 1). Four h-MDS patients are not included here for the lack of cytogenetic data. There were more patients of Int-1 risk in h-MDS group than in NH-MDS group (P ¼ 0.015).

Genetic and epigenetic alterations in h-MDS and NH-MDS The comparison of genetic and epigenetic alterations between h-MDS and NH-MDS is summarized in Table 2. The patients with h-MDS had lower incidences of RAS and AML1 mutations and SOCS1 and SHP1 hypermethylation than those with NH-MDS (5.3 vs 11.9%, 5.3 vs 14.3%, 29.4 vs 45.8%, 52.9 vs 64.3%, respectively), but the differences were not statistically significant. There was no compelling difference in other genetic or epigenetic alterations between h-MDS and NH-MDS patients.

Survival analysis On the basis of IPSS, 33 h-MDS patients were separated into the lower-risk group (including ‘low’ and ‘Int-1’) and the higher-risk group (including ‘Int-2’ and ‘high’). Noticeably, there was a significant survival difference between these two groups in h-MDS patients (median survival 112 vs 16 months, P ¼ 0.002) (Figure 1a), as in NH-MDS patients (Figure 1b). With a median follow-up duration of 98 months in 187 evaluable patients, the cumulated incidence of acute leukemic transformation at 7 years was 8.1% for h-MDS patients and 28.0% for NH-MDS patients (P ¼ 0.004) (Figure 2). Furthermore,


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Figure 2 The comparison of acute leukemic transformation rate between hypoplastic myelodysplastic syndrome (MDS) and normo-/ hypercellular MDS. Among total MDS patients except for two patients who was lost to follow-up soon after diagnosis, hypoplastic MDS patients were less prone to acute leukemic transformation than normo-/hypercellular MDS patients (P ¼ 0.004).

Variables included were age, gender, bone marrow blast percentage, marrow hypocellularity, FAB classification, acute leukemic transformation, chromosome changes and genetic changes. A multivariate model was derived and the P-value of the Omnibus test of model coefficients was o0.001. Parameters of independent significance for overall survival were age, marrow hypocellularity, RA with excess of blast, RA with excess of blast-T, monosomy 5 or 5q deletion and monosomy 7 or 7q deletion (Table 3).

Discussion

Figure 1 The applicability of International Prognostic Scoring System (IPSS) in hypoplastic myelodysplastic syndrome (MDS) and normo-/ hypercellular MDS, respectively: (a) Kaplan–Meier survival curves of 33 hypoplastic MDS patients showing longer survival of patients with ‘low’ and ‘intermediate (Int)-1’ risks than those with ‘Int-2’ and ‘high’ risks (P ¼ 0.002). (b) Kaplan–Meier survival curves of 138 normo-/hypercellular MDS patients showing longer survival of patients with ‘low’ and ‘Int-1’ risks than those with ‘Int-2’ and ‘high’ risks (Po0.001). Among 152 normo-/hypercellular MDS patients, 13 patients could not be classified by IPSS and one patient was lost to follow-up soon after diagnosis was performed.

the median overall survival was significantly longer in h-MDS than in NH-MDS patients (58 vs 24 months, P ¼ 0.003) (Figure 3a). In subgroup analysis, the survival difference between h-MDS and NH-MDS patients remained significant only among the patients categorized as ‘low’ or ‘Int-1’ risk (P ¼ 0.01) (Figure 3b), but not among those with ‘Int-2’ or ‘high’ risk (P ¼ 0.405) (Figure 3c). A Cox regression model was used to find out significant prognostic factors for survival among overall MDS patients.

In our series, 19.6% of MDS patients had h-MDS, a percentage slightly higher than that (8–19%) reported in literature.2,17,28–36 This could be explained by the exclusion of chronic myelomonocytic leukemia in our series. Chronic myelomonocytic leukemia has been reclassified into the category of myelodysplastic/myeloproliferative diseases in the new WHO (World Health Organization) classification in 2001.37 Its clinical presentation and prognosis are distinct from MDS.38 So it is necessary to sequester the influence of chronic myelomonocytic leukemia on the comparison of clinical parameters and prognosis between h-MDS and NH-MDS. According to our result, h-MDS patients had lower initial counts of white blood cells, lower marrow blast percentage and a higher frequency of FAB subtype RA than NH-MDS patients, findings similar to other reports.2,17,32 As for the cytogenetic results, the frequency of clonal chromosomal abnormalities was similar between h-MDS and NH-MDS patients (42.4 vs 47.9%, P ¼ 0.580), and there was no difference in the distribution of single, double and complex aberrations between these two groups of patients. This indirectly helped to exclude the possibility of blurred boundaries between h-MDS and aplastic anemia in our series. However, while 26 (18.3%) out of 142 NH-MDS patients who had cytogenetic study showed 7/7q, none of the 19 h-MDS patients had the same change Leukemia


548 Table 3 Significant parameters for overall survival of all MDS patients in the Cox regression model Variables Marrow hypocellularity Age 7 or 7q RAEB 5 or 5q RAEB-T

Odds ratio

P-value

0.533 1.015 3.04 5.35 5.62 17.29

0.033 0.022 0.015 0.001 0.001 o0.001

Abbreviations: MDS, myelodysplastic syndrome; RAEB, refractory anemia with excess of blast; RAEB-T, RAEB in transformation; 5, monosomy 5; 5q, 5q deletion; 7, monosomy 7; 7q, 7q deletion.

Figure 3 The comparison of prognosis between hypoplastic myelodysplastic syndrome (MDS) and normo-/hypercellular MDS. (a) A significant survival benefit of hypoplastic MDS over normo-/hypercellular MDS (P ¼ 0.003) is denoted by the Kaplan–Meier curve. (b) Among patients with ‘low’ and ‘intermediate (Int)-1’ risks, hypoplastic MDS patients had better survival than normo-/hypercellular MDS patients. The P-value of the log-rank test is 0.01. (c) Among patients with ‘Int-2’ and ‘high’ risks, there was no significant difference of overall survival between hypoplastic MDS and normo-/hypercellular MDS patients. The P-value of the log-rank test is 0.405.

Leukemia

(P ¼ 0.022). The reports concerning chromosomal aberrations in h-MDS are limited (2, 17 and 39). None of the nine h-MDS patients reported by Nand and Godwin2 harbored 7/7q and only one out of 23 such patients reported by Tuzuner et al.39 showed this abnormality. On the contrary, Maschek et al.17 demonstrated 7 in two out of the six h-MDS patients. No comparison between h-MDS and NH-MDS patients in the occurrence of 7/7q was done in these three reports. Further studies on more patients are needed to clarify whether the variation in the frequency of 7/7q in h-MDS among these reports may represent the difference of the pathogenesis of h-MDS in different geographical areas. For comparing and delineating different pathogenesis between h-MDS and NH-MDS, we performed analysis of an array of genetic and epigenetic markers as described above. Although AML1 and RAS mutations and SOCS-1 hypermethylation, all associated with poor survival,7,24,40 occurred more frequently in NH-MDS patients than in h-MDS patients, the difference was not statistically significant, probably due to the limited number of patients studied. We think that more patients are needed to demonstrate the postulated difference. To identify different survival groups in h-MDS patients, we took advantage of IPSS for risk stratification. Obviously, in our series, h-MDS patients of lower risks (that is, ‘low’ or ‘Int-1’) had a significantly longer survival (112 vs 16 months, P ¼ 0.002) than those of higher risks (that is, ‘Int-2’ or ‘high’). To the best of our knowledge, this is the first study to demonstrate that IPSS remains applicable in this distinctive clinical entity. Our Cox regression model revealed that marrow hypocellularity is an independent parameter of overall survival among all MDS patients. Therefore, the comparison of prognosis between h-MDS and NH-MDS would be reasonable and informative. It was demonstrated that the median survival of h-MDS patients was significantly longer than NH-MDS patients (58 vs 24 months, P ¼ 0.003), particularly among those categorized as lower risks according to IPSS (that is, ‘low’ or ‘Int-1’) (112 vs 32 months, P ¼ 0.01). The findings that h-MDS patients had a lower frequency of 7/7q and a trend of lower prevalence of RAS and AML1 mutations and SOCS1 hypermethylation, all associated with poor prognosis, than NH-MDS patients in this study might explain the difference of prognosis between these two groups of patients. The survival superiority of h-MDS over NH-MDS had been controversial in earlier reports.2,17,32,39,41 Herein, we would raise four points to explain this. First, all previous reports about the survival analyses did not stratify h-MDS patients further by IPSS so that the interpretation of analysis results would be interfered. Second, the population number was small and only a few patients had cytogenetic data whereby h-MDS patients


549 could be overlooked for aplastic anemia. Third, secondary MDS often consists of chromosome 7 abnormalities and presents with bone marrow hypocellularity so that it would be categorized into Int-2- or high-risk group in IPSS and is associated with poor prognosis. In our study, we only recruited patients with primary MDS. Finally, we would like to emphasize the pronounced influence of hematopoietic stem cell transplantation on the prognosis of MDS patients. In survival analysis, our patients receiving hematopoietic stem cell transplantation were censored at the time of conditioning, whereas it was not mentioned in prior reports. In summary, hypoplastic MDS is a distinct subgroup of MDS and is characterized by lower white blood cell counts and marrow blast percentage, preponderance of RA and lower incidence of chromosome 7 abnormalities. There was a trend of lower incidence of RAS and AML1 mutations and SOCS-1 hypermethylation in h-MDS patients. We propose that IPSS can be applied to the prognostic prediction of h-MDS patients. Hypocellularity of the bone marrow is a crucial prognostic factor for MDS patients, especially in the risk groups of ‘low’ and ‘Int-1.’

Acknowledgements This work was sponsored in part by grants from the National Science Council of Taiwan NSC 94-2314-B-002-143 and 95-2314-B-002-042. We are grateful to Ms Fen-Yu Lee and Ms Min-Chih Liu for their help in chromosome study.

References 1 Barrett J, Saunthararajah Y, Molldrem J. Myelodysplastic syndrome and aplastic anemia: distinct entities or diseases linked by a common pathophysiology? Semin Hematol 2000; 37: 15–29. 2 Nand S, Godwin JE. Hypoplastic myelodysplastic syndrome. Cancer 1988; 62: 958–964. 3 Chen B, Zhao WL, Jin J, Xue YQ, Cheng X, Chen XT et al. Clinical and cytogenetic features of 508 Chinese patients with myelodysplastic syndrome and comparison with those in Western countries. Leukemia 2005; 19: 767–775. 4 Lee JH, Lee JH, Shin YR, Lee JS, Kim WK, Chi HS et al. Application of different prognostic scoring systems and comparison of the FAB and WHO classifications in Korean patients with myelodysplastic syndrome. Leukemia 2003; 17: 305–313. 5 Greenberg PL. Apoptosis and its role in the myelodysplastic syndromes: implications for disease natural history and treatment. Leuk Res 1998; 22: 1123–1136. 6 Tien HF, Tang JH, Tsay W, Liu MC, Lee FY, Wang CH et al. Methylation of the p15(INK4B) gene in myelodysplastic syndrome: it can be detected early at diagnosis or during disease progression and is highly associated with leukaemic transformation. Br J Haematol 2001; 112: 148–154. 7 Wu SJ, Yao M, Chou WC, Tang JL, Chen CY, Ko BS et al. Clinical implications of SOCS1 methylation in myelodysplastic syndrome. Br J Haematol 2006; 135: 317–323. 8 Backx B, Broeders L, Touw I, Lowenberg B. Blast colony-forming cells in myelodysplastic syndrome: decreased potential to generate erythroid precursors. Leukemia 1993; 7: 75–79. 9 Kook H, Zeng W, Guibin C, Kirby M, Young NS, Maciejewski JP. Increased cytotoxic T cells with effector phenotype in aplastic anemia and myelodysplasia. Exp Hematol 2001; 29: 1270–1277. 10 Nakao M, Horiike S, Fukushima-Nakase Y, Nishimura M, Fujita Y, Taniwaki M et al. Novel loss-of-function mutations of the haematopoiesis-related transcription factor, acute myeloid leukaemia 1/runt-related transcription factor 1, detected in acute myeloblastic leukaemia and myelodysplastic syndrome. Br J Haematol 2004; 125: 709–719. 11 Georgiou G, Karali V, Zouvelou C, Kyriakou E, Dimou M, Chrisochoou S et al. Serial determination of FLT3 mutations in

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myelodysplastic syndrome patients at diagnosis, follow up or acute myeloid leukaemia transformation: incidence and their prognostic significance. Br J Haematol 2006; 134: 302–306. Paquette RL, Landaw EM, Pierre RV, Kahan J, Lubbert M, Lazcano O et al. N-ras mutations are associated with poor prognosis and increased risk of leukemia in myelodysplastic syndrome. Blood 1993; 82: 590–599. Tien HF, Wang CH, Chuang SM, Chow JM, Lee FY, Liu MC et al. Cytogenetic studies, ras mutation, and clinical characteristics in primary myelodysplastic syndrome. A study on 68 Chinese patients in Taiwan. Cancer Genet Cytogenet 1994; 74: 40–49. Greenberg P, Cox C, LeBeau MM, Fenaux P, Morel P, Sanz G et al. International scoring system for evaluating prognosis in myelodysplastic syndromes. Blood 1997; 89: 2079–2088. Bennett JM, Catovsky D, Daniel MT, Flandrin G, Galton DA, Gralnick HR et al. Proposals for the classification of the myelodysplastic syndromes. Br J Haematol 1982; 51: 189–199. Tien HF, Wang CH, Chen YC, Shen MC, Lin DT, Lin KH. Characterization of acute myeloid leukemia (AML) coexpressing lymphoid markers: different biologic features between T-cell antigen positive and B-cell antigen positive AML. Leukemia 1993; 7: 688–695. Maschek H, Kaloutsi V, Rodriguez-Kaiser M, Werner M, Choritz H, Mainzer K et al. Hypoplastic myelodysplastic syndrome: incidence, morphology, cytogenetics, and prognosis. Ann Hematol 1993; 66: 117–122. Tuzuner N, Cox C, Rowe JM, Bennett JM. Bone marrow cellularity in myeloid stem cell disorders: impact of age correction. Leuk Res 1994; 18: 559–564. Brodsky RA, Jones RJ. Aplastic anaemia. Lancet 2005; 365: 1647–1656. Chou WC, Tang JL, Lin LI, Yao M, Tsay W, Chen CY et al. Nucleophosmin mutations in de novo acute myeloid leukemia: the age-dependent incidences and the stability during disease evolution. Cancer Res 2006; 66: 3310–3316. Harada H, Harada Y, Niimi H, Kyo T, Kimura A, Inaba T. High incidence of somatic mutations in the AML1/RUNX1 gene in myelodysplastic syndrome and low blast percentage myeloid leukemia with myelodysplasia. Blood 2004; 103: 2316–2324. Lin LI, Chen CY, Lin DT, Tsay W, Tang JL, Yeh YC et al. Characterization of CEBPA mutations in acute myeloid leukemia: most patients with CEBPA mutations have biallelic mutations and show a distinct immunophenotype of the leukemic cells. Clin Cancer Res 2005; 11: 1372–1379. Shih LY, Huang CF, Wu JH, Lin TL, Dunn P, Wang PN et al. Internal tandem duplication of FLT3 in relapsed acute myeloid leukemia: a comparative analysis of bone marrow samples from 108 adult patients at diagnosis and relapse. Blood 2002; 100: 2387–2392. Chen CY, Lin LI, Tang JL, Tsay W, Chang HH, Yeh YC et al. Acquisition of JAK2, PTPN11, and RAS mutations during disease progression in primary myelodysplastic syndrome. Leukemia 2006; 20: 1155–1158. Goemans BF, Zwaan CM, Miller M, Zimmermann M, Harlow A, Meshinchi S et al. Mutations in KIT and RAS are frequent events in pediatric core-binding factor acute myeloid leukemia. Leukemia 2005; 19: 1536–1542. Chen CY, Tsay W, Tang JL, Shen HL, Lin SW, Huang SY et al. SOCS1 methylation in patients with newly diagnosed acute myeloid leukemia. Genes Chromosomes Cancer 2003; 37: 300–305. Oka T, Ouchida M, Koyama M, Ogama Y, Takada S, Nakatani Y et al. Gene silencing of the tyrosine phosphatase SHP1 gene by aberrant methylation in leukemias/lymphomas. Cancer Res 2002; 62: 6390–6394. Bartl R, Frisch B, Baumgart R. Morphologic classification of the myelodysplastic syndromes (MDS): combined utilization of bone marrow aspirates and trephine biopsies. Leuk Res 1992; 16: 15–33. Delacretaz F, Schmidt PM, Piguet D, Bachmann F, Costa J. Histopathology of myelodysplastic syndromes. The FAB classification (proposals) applied to bone marrow biopsy. Am J Clin Pathol 1987; 87: 180–186. Kitagawa M, Kamiyama R, Takemura T, Kasuga T. Bone marrow analysis of the myelodysplastic syndromes: histological and Leukemia


550

31

32 33

34

35

Leukemia

immunohistochemical features related to the evolution of overt leukemia. Virchows Arch B Cell Pathol Incl Mol Pathol 1989; 57: 47–53. Lambertenghi-Deliliers G, Annaloro C, Oriani A, Soligo D, Pozzoli E, Polli EE. Prognostic relevance of histological findings on bone marrow biopsy in myelodysplastic syndromes. Ann Hematol 1993; 66: 85–91. Mangi MH, Mufti GJ. Primary myelodysplastic syndromes: diagnostic and prognostic significance of immunohistochemical assessment of bone marrow biopsies. Blood 1992; 79: 198–205. Rios A, Canizo MC, Sanz MA, Vallespi T, Sanz G, Torrabadella M et al. Bone marrow biopsy in myelodysplastic syndromes: morphological characteristics and contribution to the study of prognostic factors. Br J Haematol 1990; 75: 26–33. Toyama K, Ohyashiki K, Yoshida Y, Abe T, Asano S, Hirai H et al. Clinical and cytogenetic findings of myelodysplastic syndromes showing hypocellular bone marrow or minimal dysplasia, in comparison with typical myelodysplastic syndromes. Int J Hematol 1993; 58: 53–61. Tricot G, De Wolf-Peeters C, Hendrickx B, Verwilghen RL. Bone marrow histology in myelodysplastic syndromes. I. Histological findings in myelodysplastic syndromes and comparison with bone marrow smears. Br J Haematol 1984; 57: 423–430.

36 Yoshida Y, Oguma S, Uchino H, Maekawa T. Refractory myelodysplastic anaemias with hypocellular bone marrow. J Clin Pathol 1988; 41: 763–767. 37 Jaffe ES. Pathology and Genetics of Tumours of Haematopoietic and Lymphoid Tissues. IARC Press: Lyon. Oxford University Press: Oxford, 2001, pp 47. 38 Harris NL, Jaffe ES, Diebold J, Flandrin G, Muller-Hermelink HK, Vardiman J et al. World Health Organization classification of neoplastic diseases of the hematopoietic and lymphoid tissues: report of the Clinical Advisory Committee meetingAirlie House, Virginia, November 1997. J Clin Oncol 1999; 17: 3835–3849. 39 Tuzuner N, Cox C, Rowe JM, Watrous D, Bennett JM. Hypocellular myelodysplastic syndromes (MDS): new proposals. Br J Haematol 1995; 91: 612–617. 40 Chen CY, Lin LI, Tang JL, Ko BS, Tsay W, Chou WC et al. RUNX1 gene mutation in primary myelodysplastic syndromeFthe mutation can be detected early at diagnosis or acquired during disease progression and is associated with poor outcome. Br J Haematol 2007; 139: 405–414. 41 Riccardi A, Giordano M, Girino M, Cazzola M, Montecucco CM, Cassano E et al. Refractory cytopenias: clinical course according to bone marrow cytology and cellularity. Blut 1987; 54: 153–163.