Every case of essential thrombocythemia should be tested for the Philadelphia chromosome

Essential thrombocythemia (ET) and chronic myelogenous leukemia (CML) usually present with distinctive features. Citing experience with cases that overlap, the Polycythemia Vera Study Group recommends that negative tests for the Philadelphia chromosome be obtained before diagnosing ET. We describe two young women presenting with features absolutely typical for ET, including extreme thrombocytosis, no leukocytosis, no basophilia, no peripheral immature cells, and no splenomegaly. Severe thrombotic complications ensued: multiple cerebrovascular thromboemboli, pulmonary emboli, and miscarriage in one and myocardial infarction in the other. By 4 years, both developed leukocytosis, extreme basophilia, and circulating blasts, typical of accelerated CML. Cytogenetic studies were then performed, revealing the Philadelphia chromosome. Imatinib produced rapid clearing of blasts and basophils, but one woman later succumbed after allogeneic bone marrow transplant and the other has not achieved a major cytogenetic response. We conclude that CML can present in identical fashion as ET. The mandate for routine Philadelphia chromosome testing is magnified by the availability of targeted therapy and its greater efficacy in early stage disease.     

Multivariate analysis of prognostic factors influencing survival in chronic myelogenous leukemia

Prognostic significance of disease features obtained at the time of initial diagnosis was analyzed in 90 patients with chronic myelogenous leukemia (CML) in chronic phase. Median survival of this population was 45.9 months. Univariate analysis revealed that splenomegaly, bone marrow basophils, bone marrow blasts, peripheral blood blasts, and bone marrow eosinophils were significant prognostic factors for survival, and that peripheral blood leukocytes counts, hemoglobin concentration, performance status, age and lymphadenopathy were factors with border line significance. There were multiple interrelationship among these disease features. Multivariate regression analysis identified that age, hemoglobin concentration, and bone marrow blasts were independent primarily significant prognostic factors for survival. The Cox model generated with three variables of age, hemoglobin concentration, and percent blasts in bone marrow provided a useful representation of risk status in the population. A hazard function derived from the patients population segregated patients into three groups with significantly different survival patterns: A lower risk group, an intermediate group and a high risk group of patients with median survival of 57.8, 49.8 and 38.4 months respectively. Survival after CML blast crisis was short and overall median survival of 54 patients with CML blast crisis was 6.4 months. A sole prognostic factor for survival in blast crisis identified by multivariate analysis was blast cell type at CML blast crisis and patients with lymphoid phenotype had a good prognosis with median survival of 9.8 months. Median survival of myeloid crisis was 4.2 months. No other disease features were identified as significant prognostic factors in the present patient population.     

The importance of cytogenetic studies in adult acute lymphocytic leukemia

PURPOSE: The prognostic importance of pretreatment bone marrow cytogenetic studies in adults with acute lymphocytic leukemia treated at a single institution, with an identical treatment program, is described. PATIENTS AND METHODS: A total of 105 patients with a documented morphologic diagnosis of acute lymphocytic leukemia were reviewed for the purpose of this analysis. All patients had an extensive workup at presentation, and cytogenetic analysis was performed in 103 patients, using the Giemsa banding technique with trypsin pretreatment on 24-hour cultured cells. RESULTS: The specific cytogenetic classification in the 103 patients who had the karyotypic analysis was as follows: diploid 27%; Philadelphia chromosome-positive 13%; hyperdiploid 12%; B-cell karyotype 6%; 6q- and 14q+ abnormalities 4%; pseudodiploid 8%; hypodiploid 2%; and insufficient metaphases 28%. B-cell, 6q- or 14q+, and Philadelphia chromosome-positive karyotypes tended to correlate with other known negative prognostic factors. Patients with diploid, hyperdiploid, pseudodiploid, and hypodiploid karyotypes or with insufficient metaphases could be combined into one group with a favorable prognosis. In this group, the remission rate with induction chemotherapy was 89%, the median complete remission duration was 26 months, and the median survival was 25 months, with a 3-year survival rate of 45%. Patients with Philadelphia chromosome-positive, B-cell, and 6q- or 14q+ abnormalities collectively had an unfavorable prognosis. Their response rate to induction chemotherapy was 65%, the median response duration was 7 months, and the median survival was 8 months, with a 3-year survival rate of less than 10%. CONCLUSION: We conclude that the pretreatment bone marrow karyotype is an important part of the evaluation of adults with acute lymphocytic leukemia and provides significant prognostic information.     

Blast crisis of Philadelphia chromosome-positive chronic myelocytic leukemia (CML)

Summary We have studied the clinical courses of 69 patients with blastic crises of Philadelphia chromosome positive CML to identify parameters that were associated with an increased response rate or survival. Cytogenetic analysis at the time of blastic transformation revealed additional chromosome changes in 70% of the patients tested. Bone marrow fibrosis was detected in 58% of evaluable patients. Lymphoblastic transformation was seen in 28% of the patients tested with cell surface marker analysis. The value of 5'-nucleotidase as a marker for distinguishing lymphoid from non-lymphoid blast crisis was confirmed. Of 57 evaluable patients, 23 (40%) responded to therapy (CR/PR longer than 14 days). Median survival was 75 days. Longer survival was related to the following factors: Ph¹-chromosome as the only detectable cytogenetic abnormality; lymphoblastic transformation; no bone marrow fibrosis; high percentage of blasts and promyelocytes in the bone marrow, and response to therapy. No prognostic significance was associated with age, sex, Tdt, LDH, spleen size, duration of the chronic phase of the disease, white blood cell count, Hb, platelet count and percentages of basophils, eosinophils, erythroblasts and blasts and promyelocytes in the peripheral blood. These data confirm the poor prognosis of patients with blastic crisis of CML treated by conventional chemotherapy.     

Pretreatment cytogenetics add to other prognostic factors predicting complete remission and long-term outcome in patients 60 years of age or older with acute myeloid leukemia: results from Cancer and Leukemia Group B 8461

We investigated the relative prognostic significance of cytogenetics in 635 adult acute myeloid leukemia (AML) patients 60 years of age or older treated on front-line protocols. Classification trees and tree-structured survival analysis (TSSA) were used to identify important cytogenetic groups, and their prognostic significance was then assessed in multivariable analysis (MVA). Overall, 48.5% achieved complete remission (CR); 6.6% survived at 5 years. Complex karyotypes with at least 3 abnormalities (complex > or = 3) and a group including "rare aberrations" predicted lower CR rates (25% and 30%) versus other patients (56%). Compared with complex > or = 3, the odds of CR were significantly higher for noncomplex karyotypes without rare aberrations on MVA. Cytogenetically, complex > or = 5 predicted inferior disease-free survival on TSSA, remaining significant on MVA together with white blood cell count (WBC), sex, and age. For survival, complex > or = 5, rare aberrations, and core-binding factor (CBF) abnormalities were prognostic (P < .001), with 5-year survivals of 0%, 0%, and 19.4%, respectively, and 7.5% for remaining patients. Together with WBC, marrow blasts, sex, and age, the cytogenetic groups remained significant on MVA. In conclusion, pretreatment cytogenetics adds to other prognostic factors in older AML patients. Patients with complex > or = 5 appear to benefit minimally from current treatment and are better suited for investigational therapy or supportive care.     

Prevalence and clinical characteristics of myelodysplastic syndrome with bone marrow eosinophilia or basophilia

By retrospectively analyzing 288 patients with de novo myelodysplastic syndrome (MDS), we sought to determine the prevalence and clinical characteristics of bone marrow eosinophilia and basophilia that were detected at presentation. Bone marrow eosinophilia and basophilia were defined as a differential count of each cell type exceeding 5.0% and 1.0%, respectively. Of 288 patients with MDS, 36 (12.5%) fulfilled this criterion for bone marrow eosinophilia (MDS-Eos); 34 patients (11.8%) showed basophilia (MDS-Bas), and 11 (3.8%) satisfied both criteria (MDS-EosBas). The remaining 229 patients had neither eosinophilia nor basophilia in their bone marrow (MDS(-/-)) at presentation. Cytogenetic analysis was carried out on unstimulated bone marrow cells obtained from 264 patients. When the cytogenetic categorization of the IPSS (International Prognostic Scoring System) for MDS was applied, significantly higher numbers of MDS-Eos and MDS-Bas patients had chromosomal abnormalities carrying intermediate or poor prognosis, compared with the MDS(-/-) patients. Specific chromosomal abnormalities and complex karyotypes were associated with MDS-Eos and/or MDS-Bas. In accordance with these results, the overall survival rate was significantly lower, and the evolution to acute myelogenous leukemia (AML) occurred more frequently in the MDS-Eos and MDS-Bas than in the MDS(-/-) patients. Multivariate analysis demonstrated that bone marrow basophilia was an independent risk factor for evolution to AML. Our study indicates that bone marrow eosinophilia and basophilia in patients with MDS predict a poorer prognosis.     

Early prediction of response in patients with relapsed or refractory Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) treated with imatinib

Imatinib has pronounced but brief antileukemic activity in advanced Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+)ALL). We assessed the prognostic impact of pretreatment disease features and the early bone marrow (BM) response in 68 consecutive patients with Ph(+)ALL receiving imatinib salvage therapy. A complete hematologic or marrow response was achieved by 92% of patients with BM blasts below 5% on day 14, whereas 62.5% of patients with more than 5% BM blasts on day 14 were nonresponders. Similarly, time to progression (TTP) was superior in patients with a good day 14 response (5.2 versus 0.9 months; P <.0001). Prior complete remission of less than 6 months, white blood cell count of more than 10 x 10(9)/L, circulating peripheral blood blasts at diagnosis, additional Philadelphia chromosomes, or at least 2 Bcr-Abl fusion signals were associated with significantly inferior remission rate and response duration. In patients without poor prognostic features, single-agent imatinib may be appropriate before transplant salvage therapy. Conversely, patients with clinically or cytogenetically defined poor-risk features are candidates for trials of upfront imatinib in combination with other agents.     

Chronic myelogenous leukemia in blast crisis. Analysis of 242 patients

Two hundred forty-two patients with Philadelphia chromosome-positive chronic myelogenous leukemia in blast crisis were reviewed to identify significant biologic and prognostic associations. Twenty percent of patients had lymphoid blast crisis. Clonal evolution was present in 60 percent of patients at blast crisis and involved most frequently the development of a double Philadelphia chromosome, trisomy 8, or isochromosome 17. The overall median survival from blast crisis was 18 weeks. Patient characteristics demonstrated to have significant association with short survival were: anemia; thrombocytopenia; myeloid or undifferentiated blast cell morphology; clonal evolution involving the presence of a double Philadelphia chromosome, trisomy 8, or isochromosome 17; and low marrow blast percentage. Of 195 patients who received therapy for blast crisis, complete remission was achieved in 44 (23 percent) patients, and 24 (13 percent) patients had a partial remission or hematologic improvement. Lower complete remission rates were associated with old age, thrombocytopenia, myeloid or undifferentiated blast cell morphology, clonal evolution--especially isochromosome 17 and trisomy 8--and long interval from diagnosis to onset of blast crisis. A multivariate analysis identified two characteristics to have independent prognostic importance for both survival and remission: platelet counts and blast cell morphology. In addition, clonal evolution had additive prognostic value for survival (double Philadelphia chromosome) and for response (isochromosome 17). The beneficial association of therapy with survival was demonstrated by the significantly longer median survival of patients treated since 1981 compared with those treated earlier, even after accounting for the pretreatment prognostic factors, and by the significant improvement in survival of patients achieving remission using the "landmark" analysis technique.     

Primary myelofibrosis: 2012 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW: Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by stem cell-derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival. DIAGNOSIS: Diagnosis is based on bone marrow morphology. The presence of fibrosis, JAK2/MPL mutation or +9/13q- cytogenetic abnormality is supportive but not essential for diagnosis. Prefibrotic PMF mimics essential thrombocythemia in its presentation and the distinction is prognostically relevant. Differential diagnosis of myelofibrosis should include chronic myelogenous leukemia, myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia. RISK STRATIFICATION: The Dynamic International Prognostic Scoring System-plus (DIPSS-plus) prognostic model for PMF can be applied at any point during the disease course and uses eight independent predictors of inferior survival: age >65 years, hemoglobin <10 g/dL, leukocytes >25 × 10(9) /L, circulating blasts ≥1%, constitutional symptoms, red cell transfusion dependency, platelet count <100 × 10(9) /L, and unfavorable karyotype (i.e., complex karyotype or sole or two abnormalities that include +8, -7/7q-, i(17q), inv(3), -5/5q-, 12p- or 11q23 rearrangement). The presence of 0, 1, "2 or 3," and ≥4 adverse factors defines low, intermediate-1, intermediate-2, and high-risk disease with median survivals of ~15.4, 6.5, 2.9, and 1.3 years, respectively. A >80% two-year mortality is predicted by monosomal karyotype, inv(3)/i(17q) abnormalities, or any two of circulating blasts >9%, leukocytes ≥40 × 10(9) /L or other unfavorable karyotype. RISK-ADAPTED THERAPY: Observation alone is adequate for asymptomatic low/intermediate-1 risk disease. Allogeneic stem cell transplantation or experimental drug therapy is considered for intermediate-2/ high risk disease. Conventional or experimental drug therapy is reasonable for symptomatic intermediate-1 risk disease. Splenectomy and low-dose radiotherapy are used for drug-refractory splenomegaly. Radiotherapy is also used for the treatment of non-hepatosplenic EMH, PMF-associated pulmonary hypertension, and extremity bone pain.     

Cytogenetics of chronic myelogenous leukemia (CML) correlated to the histopathology of bone marrow biopsies

Summary Cytogenetic findings were correlated to histopathological bone marrow findings evaluated simultaneously in 103 patients with chronic myelogenous leukemia (CML). CML was subtyped histologically according to the number of megakaryocytes and increase of fibers or blasts within the bone marrow. The Philadelphia chromosome (Ph1) was found in 88.3% of all patients (91/103). Chromosome aberrations additional to the Ph 1-chromosome were noticed in 20 of 91 (22%) cases. The additional karyotype changes occurred significantly more frequently among patients with increase of fibers in the bone marrow compared with patients without increase of fibers or blasts (p<0.05). Karyotype changes associated with increase of fibers in Ph 1-positive cases of CML were trisomy 8 and 19, +Phl, t (1; 11), and i (17q). Ph 1-positive CML patients with additional karyotype changes had a significantly shorter survival (p<0.04) than Ph 1-positive patients without additional chromosome aberrations. Our results suggest that histopathological examination of the bone marrow should be considered in the evaluation of cytogenetic markers in chronic myeloproliferative disorders.     

Cytogenetic features and prognosis analysis in Chinese patients with myelodysplastic syndrome: a multicenter study

It has been suggested that Asian and Western myelodysplastic syndrome (MDS) patients have different cytogenetic and prognostic features. In this study, we retrospectively analyzed clinical and cytogenetic data from 435 Chinese adult primary MDS patients. In addition, we evaluated the prognostic value of the World Health Organization classification as well as six prognostic scoring systems in these patients. The median follow-up time was 25.1 months (5.5–53.2). Of the 435 patients, 186 (42.8%) had died and 40 (9.2%) had progressed to acute myeloid leukemia. Multivariate analysis identified older age, higher percent of marrow blasts, and poor-risk IPSS cytogenetics as characteristics associated with worse survival and higher risk of leukemia transformation. Low platelets, hemoglobin, and mean corpuscular volume were independent factors associated only with worse survival. Among the 424 patients in whom the results of cytogenetic analyses were available, 164 (38.7%) showed karyotypic abnormalities. Incidence of trisomy 8 was common but sole del(5q) was rare in Chinese MDS patients. For predicting survival, most scoring systems were meaningful for stratifying patients into different subgroups, with the exception of the WPSS scoring system. For predicting leukemia evolution, the Spanish scoring system was most effective. Patients with RAEB-2 showed different prognoses from those with RAEB-1. However, there was no significant difference in prognoses between patients with refractory cytopenia with multilineage dysplasia (RCMD) from RA or RARS. In summary, this analysis indicated the presence of a different cytogenetic pattern as well as prognostic features in Chinese MDS patients.     

Relationship of pretreatment lymphoblast proliferative activity and prognosis in 97 children with acute lymphoblastic leukemia

We have analyzed the pretreatment 3H-thymidine labeling indices in blood and marrow blast cells from 97 children with acute lymphoblastic leukemia (ALL) and circulating blasts. The median marrow labeling index (LI) was 6.2% (range 0.8%--32.7%) and the median blood LI, 3.2% (range 0.3%--20%). Blood LI was significantly correlated with leukocyte count and rosette-forming (E+) lymphoblasts but not with central nervous system leukemia or thymic mass at diagnosis. Marrow LI was related to E+ blasts only. In children with E+ leukemia, both blood and marrow LIs were significantly higher than values for other ALL subtypes (p less than 0.01) excluding undifferentiated ALL, which was characterized by an increased blood LI. Eighteen patients had a blood LI that either equaled or exceeded the marrow LI; apart from age, the clinical features, blast phenotypes, and treatment responses of this group were similar to those of patients with blood LI less than marrow LI. Among 51 patients assessed for treatment response, the estimated median length of remission was significantly shorter for those with a blood LI greater than 4% (p = 0.002) or a marrow LI greater than 6% (p = 0.011). By Cox-regression analysis, the pretreatment proliferative activity of blood and marrow blasts, unlike other initial features studied, added significant prognostic information to leukocyte count in these patients with circulating blasts. The findings provide a cogent explanation for the differential clinical responsiveness of commonly recognized ALL subclasses.     

Myelodysplastic syndrome associated with marked eosinophilia and basophilia]

Myelodysplastic syndrome (refractory anemia with excess of blasts; RAEB) with marked basophilia and eosinophilia is described. An 82-year-old male was admitted to our hospital because of severe normocytic normochromic anemia (Hb 5.6 g/dl). The white cell count was 9,200/microliters with marked basophilia (34.5%) and eosinophilia (19.5%). The bone marrow aspiration also revealed both basophilia and eosinophilia, with blast contents of 9%. Diagnosis of RAEB was established. Although the treatment with red cell transfusion and ubenimex (Bastatin) was started, anemia was not improved. A karyotype of the bone marrow cells from this patient showed 47, XY, +8, i (17q), which has been observed as additional chromosomal abnormalities in blastic crisis of chronic myelogenous leukemia. The diagnosis of CML was not compatible with this case, because Ph1 chromosome and bcr gene rearrangement were negative. It is concluded that eosinophilia and basophilia might be derived from clonal abnormalities associated with MDS.     

Increased numbers of marrow basophils may be associated with a t(6;9) in ANLL

We have characterized another subset of acute nonlymphocytic leukemia (ANLL) based on the cytogenetic and morphologic findings in a group of nine patients. Five patients had chromosomal analyses performed at the University of Chicago, two patients were studied at the All-Union Cancer Research Center in Moscow, and one patient each was studied at the University of Maryland and at Fairfax Hospital in Fairfax, Virginia. All nine patients had a reciprocal translocation involving the short arm of chromosome 6 and the long arm of chromosome 9 [t(6;9)(p23;q34)]. The patients, four males and five females, ranged in age from 5 to 51 years; the median age of 38 years is lower than that typically seen in ANLL. Only two of eight treated patients entered a complete remission. Classification of bone marrow morphology according to FAB Cooperative Group criteria revealed AML-M1 in one patient, AML-M2 in four, and AMMoL-M4 in three. One patient had refractory anemia with excess blasts (RAEB) which evolved to AML-M2. All bone marrow specimens showed severe myelodysplasia, with Auer rods present in seven of the nine cases. Of note was the particular prominence of bone marrow basophils (greater than 1%) in eight of the nine (89%) patients. Among 160 evaluable patients with ANLL de novo seen at the University of Chicago whose cells lacked a t(6;9), only five (3%) had greater than 1% basophils in the marrow aspirates. It is of interest that the breakpoint in 9q involves the same chromosomal band as that in the t(9;22) observed in chronic myelogenous leukemia (CML), in which increased basophils are a prominent feature. Thus, the association of the t(6;9) with increased bone marrow basophils in ANLL may provide additional insight into the chromosomal location of genes regulating the production and/or maturation of basophils.     

5‐Azacytidine treatment for relapsed or refractory acute myeloid leukemia after intensive chemotherapy

Despite progress in the understanding of leukemia pathophysiology, the treatment of acute myeloid leukemia (AML) remains challenging. In patients with refractory or relapsed (R/R) AML, the prognosis is still poor and this group is targeted for new drug development. We reviewed the outcome of 47 patients, with R/R AML after at least one course of intensive chemotherapy, treated with 5‐azacytidine in three different French institutions. The overall response rate was 38% including complete remission in 21%, partial remission in 11%, and hematological improvement in 6% of cases. Median time to relapse was 6 (range, 1–39) months. Median overall survival was 9 months (not reached by responders vs. 4.5 months for nonresponders patients, P = 0.0001). Univariate analysis identified the absence of peripheral blood blasts and <20% bone marrow blasts as prognostic factors for both overall response and survival, but not age, ECOG/PS, type of AML, cytogenetic, status of the disease, number of previous lines of therapy, previous hematological stem cell transplantation, or white blood cells count. Bone marrow blasts percentage <20% was the only independent prognostic factor identified by multivariate analysis for overall response (P = 0.0013) and survival (P = 0.0324). Six patients in remission could proceed to an allogenic hematological stem cell transplantation. The drug‐related grade 3/4 adverse events were hematopoietic toxicities (38%) and infection (32%). In conclusion, this study suggests that a salvage therapy with 5‐azacytidine is an interesting option for patients with R/R AML after intensive chemotherapy. Prospective randomized studies are needed to demonstrate a superiority of this approach over others strategies. Am. J. Hematol. 88:601–605, 2013. © 2013 Wiley Periodicals, Inc.     

Prognostic discrimination among younger patients with chronic granulocytic leukemia: relevance to bone marrow transplantation

To obtain information relevant to the question of bone marrow transplantation, we examined the prognostic significance of disease features recorded at the time of diagnosis among 625 patients, aged 5 to 45, with Philadelphia chromosome-positive, nonblastic chronic granulocytic leukemia. The actuarial death rate for this population was 5% during the first year after diagnosis, 12% during the second year, and averaged 22.5% per year during the next eight years. Multivariable regression analysis of features recorded in nearly all cases indicated that sex, spleen size, hematocrit, platelet count, and percentage of circulating blasts were significant prognostic indicators. Analyses of additional data available in 113 to 421 cases suggested that serum lactic dehydrogenase activity, percentage of blasts in marrow, nucleated RBCs in blood, and percentage of basophils plus eosinophils might also provide useful prognostic information. A Cox model, generated with five variables representing features recorded regularly (the first five listed), permitted segregation of these patients into three groups with significantly different survival patterns. The high-risk group exhibited an actuarial mortality of 30% during the first two years after diagnosis and an annual risk of 30% thereafter. In contrast, the most favorable group had a two-year actuarial mortality of 9% and an average risk thereafter of 17% per year, with a median survival of 5 1/2 years. We conclude that it should be possible to classify potential candidates for bone marrow transplantation according to risk with conventional therapy. Such information may be useful in making decisions regarding early v deferred marrow transplantation.     

Early peripheral blood blast clearance during induction chemotherapy for acute myeloid leukemia predicts superior relapse-free survival

In childhood acute lymphoblastic leukemia (ALL), a rapid decline of circulating leukemic blasts in response to induction chemotherapy or prednisone is one of the most important prognostic factors, not only for achieving remission but also for relapse-free survival (RFS). However, in acute myeloid leukemia (AML) parameters of chemosensitivity have been restricted mainly to the rapidity of achievement of complete remission (CR) or the assessment of residual leukemic bone marrow blasts during aplasia. We hypothesized that the time to circulating peripheral blood blast clearance, as a potential surrogate for in vivo chemosensitivity, would have prognostic relevance in AML also. In a retrospective analysis of a cohort of 86 adult patients with AML receiving uniform induction and consolidation chemotherapy, we demonstrate that the time to clearance of circulating blasts during induction chemotherapy is an independent prognostic marker of RFS, superseding other known or established risk factors, including karyotype and number of inductions to achieve CR.     

N-ras mutations are associated with poor prognosis and increased risk of leukemia in myelodysplastic syndrome

To evaluate the clinical significance of N-ras mutations in the myelodysplastic syndrome (MDS) archival bone marrow samples from 252 patients were studied for the presence of N-ras exon I mutations using polymerase chain reaction amplification and differential oligonucleotide hybridization. Subsequently, clinical information about these patients was obtained and analyzed. Of 220 evaluable patients, 20 (9%) had point mutation of N-ras involving codon 12. Individuals with N- ras mutation had a significantly shorter survival period than those who were N-ras negative (P = .02). An increased risk of acute myelogenous leukemia (AML) was also found in patients with N-ras mutations (P = .005). N-ras mutations were not associated with any French-American- British (FAB) subtype, with the presence of increased myeloblasts, or with chromosomal aberrations in the bone marrow. However, the presence of increased bone marrow blasts was strongly associated with poor survival rate and risk of AML (P < .001 for each). After stratifying for the percentage of blasts, N-ras mutations remained significantly associated with shorter survival period (P = .04) and increased risk of AML (P = .02). Bone marrow cytogenetic abnormalities, particularly when multiple abnormalities were present, were significantly associated with a poor prognosis (P < .001). In conclusion, N-ras mutation, although relatively infrequent in MDS, is associated with short survival period and increased probability of developing AML.