Comparison between flow cytometry and standard PCR in the evaluation of MRD in children with acute lymphoblastic leukemia treated with the GBTLI LLA - 2009 protocol.

Minimal residual disease (MRD) monitoring is of prognostic importance in childhood acute lymphoblastic leukemia (ALL). The detection of immunoglobulin and T-cell receptor gene rearrangements by real-time quantitative PCR (RT-PCR) is considered the gold standard for this evaluation. However, more accessible methods also show satisfactory performance. This study aimed to compare MRD analysis by four-color flow cytometry (FC) and qualitative standard PCR on days 35 and 78 of chemotherapy and to correlate these data with patients' clinical characteristics. Forty-two children with a recent diagnosis of ALL, admitted to a public hospital in Brazil for treatment in accordance with the Brazilian Childhood Cooperative Group for ALL Treatment (GBTLI LLA-2009), were included. Bone marrow samples collected at diagnosis and on days 35 and 78 of treatment were analyzed for the immunophenotypic characterization of blasts by FC and for the detection of clonal rearrangements by standard PCR. Paired analyses were performed in 61/68 (89.7%) follow-up samples, with a general agreement of 88.5%. Disagreements were resolved by RT-PCR, which evidenced one false-negative and four false-positive results in FC, as well as two false-negative results in PCR. Among the prognostic factors, a significant association was found only between T-cell lineage and MRD by standard PCR. These results show that FC and standard PCR produce similar results in MRD detection of childhood ALL and that both methodologies may be useful in the monitoring of disease treatment, especially in regions with limited financial resources.

Use of the Polymerase Chain Reaction as a Complementary Method for the Detection of Central Nervous System Involvement in Children and Adolescents with Acute Lymphoblastic Leukemia.

BACKGROUND: Cytological analysis of the cerebrospinal fluid (CSF) remains the most widely used method for diagnosing central nervous system (CNS) involvement in acute lymphoblastic leukemia (ALL). This study aimed at evaluating the use of polymerase chain reaction (PCR), in comparison to other methods, for the assessment of the presence of blast cells in the CSF at the time of diagnosis of ALL. METHODS: This was a prospective, single-centre, study enrolling all patients up to the age of 18 years who were admitted to a university hospital between November 2011 and November 2014 with a diagnosis of ALL and from whom it was possible to draw a sufficient amount of CSF for analysis by conventional cytology (CT), immunophenotyping (IMP), and PCR. RESULTS: A total of 46 CSF samples from 44 ALL pediatric patients were included. CT was performed in all samples, IMP in 44, and PCR in 34. Thirteen (28.2%) samples showed positive results: two by CT, four by IMP, four by PCR, and three by both IMP and PCR. CONCLUSIONS: The results of this study showed that PCR should be considered a complementary method for the evaluation of the CSF in ALL patients at diagnosis.

Immunophenotyping of the cerebrospinal fluid as a prognostic factor at diagnosis of acute lymphoblastic leukemia in children and adolescents.

This study aimed at evaluating the use of immunophenotyping (IMP) in the identification of blast cells in the cerebrospinal fluid (CSF) of children and adolescents with acute lymphoblastic leukemia (ALL). Sixty-seven patients aged 18 years or younger were included. Fifty-five CSF samples were analyzed at initial diagnosis and 17 at the time of relapse. A cytological analysis (CA) was performed in all 72 samples, while IMP was done in 63. Blasts were identified in only three samples by CA, whereas all three samples were found negative by IMP, one of which had no isolation of nucleated cells after centrifugation. Among the samples analyzed by IMP, 11 showed a positive blast count, two of which had been inconclusive using CA. No equivalence was found between CA and IMP results (p = 0.55). CSF IMP positivity was not associated with other risk factors for ALL relapse. Among the 55 patients included at the time of diagnosis of ALL, eight relapsed during follow-up. Considering the cases of central nervous system (CNS) relapse, one of the patients belonged to the CSF IMP-positive group (11%) at diagnosis, and the other two cases, to the IMP-negative (5%) group. Detection of CSF blast cells using IMP was associated with a worse overall (p < 0.0001) and event-free survival (p < 0.0001). These results show that CSF IMP may be a useful additional method to conventional CA in the diagnosis of CNS involvement in ALL, and for the identification of high-risk subgroups that would benefit from an intensified therapy.

Comparative analysis between cytomorphology and flow cytometry methods in central nervous system infiltration assessment in oncohematological patients.

INTRODUCTION: Oncohematological patients require the evaluation for possible infiltration of the central nervous system (CNS) by neoplastic cells at diagnosis and/or during the monitoring of the chemotherapeutic treatment. Morphological analysis using conventional microscopy is considered the method of choice to evaluate the cerebrospinal fluid (CSF) samples, despite technical limitations. OBJECTIVE: This study aimed to compare the performance of the cytomorphology and flow cytometric immunophenotyping (FC) in the detection of CNS infiltration. METHOD: We evaluated 520 CSF samples collected from 287 oncohematological patients for whom the detection of neoplastic cells was simultaneously requested by cytomorphology and FC. RESULTS: Laboratory analyses revealed 435/520 (83.7%) conclusive results by the two methods evaluated, among which 385 (88.5%) were concordant. Discordance between the methods was observed in 50/435 (11.5%) samples, 45 (90%) being positive by FC. Furthermore, the FC defined the results in 69/72 (95.8%) inconclusive samples by cytomorphology. The positivity of FC was particularly higher among hypocellular samples. Among 431 samples with a cell count of < 5/µL, the FC identified neoplastic cells in 75 (17.4%), while the cytomorphology reported positive results in 26 (6%). Among the samples that presented adequate cell recovery for evaluation by both methods (506/520), the comparative analysis between FC and cytomorphology revealed a Kappa coefficient of 0.45 (CI: 0.37-0.52), interpreted as a moderate agreement. CONCLUSION: The data showed that the CSF analysis by FC helps in the definition of CNS infiltration by neoplastic cells, particularly in the cases with dubious morphological analysis or in the evaluation of samples with low cellularity.

30 Years of Experience with Non-Hodgkin Lymphoma in Children and Adolescents: a retrospective cohort study.

OBJECTIVE: Describe the clinical and demographic characteristics of pediatric patients with non-Hodgkin's lymphoma (NHL) enrolled in a tertiary unit of Pediatric Hematology between 1982-2015. PATIENTS AND METHODS: A retrospective cohort study of 140 patients aged 16 years or less with NHL. Demographic characteristics, data on diagnosis, and outcomes were analyzed. The overall survival (OS) analysis and stratification by the most frequent histological subtypes were performed using the Kaplan-Meier method. RESULTS: One hundred and thirty-six patients with de novo NHL and four with NHL as a second malignancy were analyzed. The median age at diagnosis was 6.4 years (interquartile range, 4.2 to 11.1 years); 101 patients were males. Four patients had primary immunodeficiency, four had human immunodeficiency virus, two post-liver transplantation, and one had autoimmune lymphoproliferative syndrome. The most frequent histological type was NHL of mature B- cell (B-NHL-B; 67.1%), with Burkitt's lymphoma being the most frequent subtype, and lymphoblastic lymphoma (LBL, 21.4%). The main clinical manifestation at the diagnosis was abdominal tumors (41.4%). During the follow-up time, 13 patients relapsed, but five of them reached a second remission. Thirty-five patients died, and 103 remained alive in clinical remission. No contact was possible for two patients. The OS at 5 years was 74.5% (± 3.8%). The OS estimated for patients with LBL, NHL-B, and the remaining was 80.4%±7.9%, 72.8%±4.7%, and 74.5%±11%, respectively (P = 0.58). CONCLUSION: Our results are comparable with cohorts from other middle-income countries.

Cytogenetic abnormalities, WHO classification, and evolution of children and adolescents with acute myeloid leukemia.

OBJECTIVES: To describe cytogenetic and molecular abnormalities observed in children and adolescents with acute myeloid leukemia (AML), classify AML according to the World Health Organization (WHO) classifications from 2008 and 2016, and evaluate the prognosis according to clinical characteristics and cytogenetic abnormalities. METHODS: A retrospective longitudinal study was performed on a population of 98 patients with AML, aged up to 16 years, seen in a single hospital from 2004 to 2015. RESULTS: Among the 80 patients for whom it was possible to analyze the karyotype, 78.7% had chromosomal changes, the most frequent being t(15;17)(q22;q21). Of the 86 patients for whom we had cytogenetic or molecular data, making it possible to classify their AML according to the WHO classification, 52.3% belonged to the group with recurrent genetic abnormalities, 22% to the "AML not otherwise specified" group, 18.6% to the group with myelodysplasia-related cytogenetic changes, and 7% to the group with Down syndrome-related leukemia. Five-year overall survival (OS) for the whole group was 49.7%±5.2%. In the univariate and multivariate analyses, patients with myelodysplasia-related cytogenetic changes (OS 28.1%±12.2%) and those with "AML not otherwise specified" (OS 36.1%±11.2%) had an unfavorable prognosis when compared to patients with AML with recurrent genetic abnormalities (OS 71%±5.8%) and patients with Down syndrome-related AML (OS 83%±15.2%, p=0.011). CONCLUSIONS: The results corroborate the importance of cytogenetic abnormalities as a prognostic factor and indicate the need for cooperative and prospective studies to evaluate the applicability of the WHO classification in the pediatric population.

Thiopurine S-methyltransferase (TPMT) gene polymorphism in Brazilian children with acute lymphoblastic leukemia: association with clinical and laboratory data.

The frequency of allele variants of gene TPMT*2, *3A, *3B, and *3C was estimated in a population of 116 Brazilian children with acute lymphoblastic leukemia. The association between genotype and clinical and laboratory data obtained during chemotherapy maintenance phase and the correlation of intraerythrocyte concentration of 6-mercaptopurine metabolites (6-tioguanine nucleotide nucleotides and methylmercaptopurine) were analyzed. A multiplex amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) was used in DNA amplification. Twelve patients presented TPMT gene mutation, all in heterozygous form. The most frequent allele variation was TPMT*3A (3.9%), followed by *3C (0.9%), *2 (0.4%), and *3B (0%). There was no significant association between clinical and laboratory data and the presence of mutation in TPMT gene. Of the 36 patients who were monitored for 6-mercaptopurine metabolite levels, only 1 had the mutation. In this patient, high 6-tioguanine nucleotide and low methylmercaptopurine concentrations were found. Event-free survival (EFS) for the whole group was 73.4%. There was no significant difference in event-free survival in the comparison between the groups with and without mutation (P = 0.06).

Comparative analysis between cytomorphology and flow cytometry methods in central nervous system infiltration assessment in oncohematological patients

ABSTRACT Introduction Oncohematological patients require the evaluation for possible infiltration of the central nervous system (CNS) by neoplastic cells at diagnosis and/or during the monitoring of the chemotherapeutic treatment. Morphological analysis using conventional microscopy is considered the method of choice to evaluate the cerebrospinal fluid (CSF) samples, despite technical limitations. Objective This study aimed to compare the performance of the cytomorphology and flow cytometric immunophenotyping (FC) in the detection of CNS infiltration. Method We evaluated 520 CSF samples collected from 287 oncohematological patients for whom the detection of neoplastic cells was simultaneously requested by cytomorphology and FC. Results Laboratory analyses revealed 435/520 (83.7%) conclusive results by the two methods evaluated, among which 385 (88.5%) were concordant. Discordance between the methods was observed in 50/435 (11.5%) samples, 45 (90%) being positive by FC. Furthermore, the FC defined the results in 69/72 (95.8%) inconclusive samples by cytomorphology. The positivity of FC was particularly higher among hypocellular samples. Among 431 samples with a cell count of < 5/μL, the FC identified neoplastic cells in 75 (17.4%), while the cytomorphology reported positive results in 26 (6%). Among the samples that presented adequate cell recovery for evaluation by both methods (506/520), the comparative analysis between FC and cytomorphology revealed a Kappa coefficient of 0.45 (CI: 0.37-0.52), interpreted as a moderate agreement. Conclusion The data showed that the CSF analysis by FC helps in the definition of CNS infiltration by neoplastic cells, particularly in the cases with dubious morphological analysis or in the evaluation of samples with low cellularity.

Clinical course of autoimmune hemolytic anemia: an observational study.

OBJECTIVE: Autoimmune hemolytic anemia is characterized by the production of autoantibodies against erythrocyte membrane antigens. This study was carried out to identify the clinical, immunological and outcome characteristics of autoimmune hemolytic anemia patients treated at the (HC-UFMG) Pediatric Hematology Unit and the Hemocentro de Belo Horizonte. METHODS: We evaluated 17 patients younger than 15 years old admitted from 1988 to 2003 were evaluated. Autoimmune hemolytic anemia diagnosis was based on the presence of acquired hemolysis and confirmed by positive direct Coombs polyspecific test results. Clinical, laboratory, and outcome data were obtained from patient records. RESULTS: The median age at diagnosis was 10.5 months. The direct Coombs polyspecific test was positive in 13 and negative in four patients. Monospecific testing was performed for 14 patients. The most frequent red cell autoantibody was IgG (five patients), followed by IgM in two. Thirteen patients had severe anemia and needed blood transfusions. Underlying diseases were identified in four patients: systemic lupus erythematosus, Hodgkin's lymphoma, autoimmune hepatitis and Langerhans cell histiocytosis. The remaining patients were classified as having primary disease. The median follow-up period was 11 months (5 to 23 months). Three children died, two after splenectomy and one with complications of the underlying disease. CONCLUSION: Autoimmune hemolytic anemia is rare in children and adolescents. Although patients usually respond to corticosteroids and/or immunoglobulin, fatal cases can occur. Prognosis is worse in patients with chronic underlying diseases.

Current Strategies for the Detection of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. Current treatment strategies for childhood ALL result in long-term remission for approximately 90% of patients. However, the therapeutic response is worse among those who relapse. Several risk stratification approaches based on clinical and biological aspects have been proposed to intensify treatment in patients with high risk of relapse and reduce toxicity on those with a greater probability of cure. The detection of residual leukemic cells (minimal residual disease, MRD) is the most important prognostic factor to identify high-risk patients, allowing redefinition of chemotherapy. In the last decades, several standardized research protocols evaluated MRD using immunophenotyping by flow cytometry and/or real-time quantitative polymerase chain reaction at different time points during treatment. Both methods are highly sensitive (10(-3) a 10(-5)), but expensive, complex, and, because of that, require qualified staff and frequently are restricted to reference centers. The aim of this article was to review technical aspects of immunophenotyping by flow cytometry and real-time quantitative polymerase chain reaction to evaluate MRD in ALL.

30 Years of Experience with Non-Hodgkin Lymphoma in Children and Adolescents: a retrospective cohort study

SUMMARY OBJECTIVE Describe the clinical and demographic characteristics of pediatric patients with non-Hodgkin's lymphoma (NHL) enrolled in a tertiary unit of Pediatric Hematology between 1982-2015. PATIENTS AND METHODS A retrospective cohort study of 140 patients aged 16 years or less with NHL. Demographic characteristics, data on diagnosis, and outcomes were analyzed. The overall survival (OS) analysis and stratification by the most frequent histological subtypes were performed using the Kaplan-Meier method. RESULTS One hundred and thirty-six patients with de novo NHL and four with NHL as a second malignancy were analyzed. The median age at diagnosis was 6.4 years (interquartile range, 4.2 to 11.1 years); 101 patients were males. Four patients had primary immunodeficiency, four had human immunodeficiency virus, two post-liver transplantation, and one had autoimmune lymphoproliferative syndrome. The most frequent histological type was NHL of mature B- cell (B-NHL-B; 67.1%), with Burkitt's lymphoma being the most frequent subtype, and lymphoblastic lymphoma (LBL, 21.4%). The main clinical manifestation at the diagnosis was abdominal tumors (41.4%). During the follow-up time, 13 patients relapsed, but five of them reached a second remission. Thirty-five patients died, and 103 remained alive in clinical remission. No contact was possible for two patients. The OS at 5 years was 74.5% (± 3.8%). The OS estimated for patients with LBL, NHL-B, and the remaining was 80.4%±7.9%, 72.8%±4.7%, and 74.5%±11%, respectively (P = 0.58). CONCLUSION Our results are comparable with cohorts from other middle-income countries.

RESUMO OBJETIVO Descrever as características clínicas e demográficas de pacientes pediátricos com linfoma não Hodgkin (LNH) em uma unidade terciária de Hematologia Pediátrica entre 1982-2015. PACIENTES E MÉTODOS Estudo de coorte retrospectivo de dados de prontuários de 140 pacientes com idade até 16 anos com LNH. Características demográficas e dados relativos ao diagnóstico e evolução foram analisados. A sobrevida global (SG) e estratificada pelos subtipos histológicos mais frequentes foi analisada pelo método de Kaplan-Meier. RESULTADOS Dados de 136 pacientes com LNH de novo e quatro com LNH como segunda neoplasia foram analisados. A mediana de idade ao diagnóstico foi 6,4 anos (intervalo interquartil: 4,2 a 11,1 anos); 101 pacientes eram meninos. Onze pacientes apresentavam imunodeficiência (quatro primária, quatro secundária ao vírus da imunodeficiência humana adquirida, dois pós-transplante hepático e um com síndrome linfoproliferativa autoimune). Os tipos histológicos mais frequentes foram o LNH de células B madura (LNH-B, 67,1% dos pacientes), sendo o linfoma de Burkitt o subtipo mais frequente, e o linfoma linfoblástico (LL, 21,4%). A principal manifestação clínica ao diagnóstico foi massa abdominal (41,4%). A mediana de seguimento dos sobreviventes foi 7,7 anos (intervalo interquartil: 3,3 a 10,9 anos). Treze pacientes recidivaram (cinco alcançaram segunda remissão clínica), 35 faleceram, 103 permanecem vivos em remissão completa e dois perderam o seguimento. A probabilidade de SG em cinco anos foi 74,5%±3,8%. Para os pacientes com LL, LNH-B e os demais, a SG foi 80,4%±7,9%, 72,8%±4,7% e 74,5%±11%, respectivamente (P=0,58). CONCLUSÃO Nossos resultados são comparáveis aos de outros países de renda média.

[Acute myeloid leukemia in childhood: 15-year experience in a single institution]. / Leucemia mielóide aguda na criança: experiência de 15 anos em uma única instituição.

OBJECTIVE: To investigate the survival of children with acute myeloid leukemia (AML) before and after the introduction of a Berlin-Frankfurt-Munich-83 based protocol. To analyze the prognostic impact of age, gender, nutritional status, initial white blood cell count and use of etoposide in the remission induction phase. METHODS: This partly prospective/retrospective study comprised 83 children with AML diagnosed at Hospital das Clínicas, Universidade Federal de Minas Gerais, Brazil, between 1986 and 2000. Before 1991, 15 children were treated with 2-3 pulses of cytarabin plus daunomycin, followed by several consolidation/maintenance schemes. From January 1991 to November 1992 a pilot study (n = 15) was carried out to test etoposide toxicity in the induction phase. Etoposide was randomized from December 1992 to June 1999. RESULTS: Median follow-up period was 5 years. Initial remission rates were 40 and 66% before or after the introduction of the German protocol, respectively (p = 0.11). Induction failure was largely due to death caused by infection and/or hemorrhage. The 5-year estimated probabilities of survival and of continuous complete remission were 31+/-5.4% and 49.7+/-7.4%, respectively. All 22 relapses involved the bone marrow. Age below 6 years at diagnosis was significantly associated with a poor prognosis. Sex, initial leukocyte count, and nutritional variables were not significant prognostic factors. The randomized addition of etoposide in the induction phase unexpectedly decreased the probability of complete remission at 5 years. CONCLUSIONS: The introduction of a German-based protocol in 1991 significantly improved survival and duration of first remission. No plausible explanation for the unfavorable effect of etoposide was found.

Hemophagocytic lymphohistiocytosis: a case series of a Brazilian institution.

OBJECTIVE: To describe the clinical and laboratory presentation of hemophagocytic lymphohistiocytosis in children treated at a referral institution. METHODS: A retrospective descriptive study was carried out of seven children diagnosed with hemophagocytic lymphohistiocytosis between 2010 and 2012. The criteria for diagnosis were those proposed by the Histiocyte Society. When indicated, immunochemotherapy was prescribed according to the HLH94 and HLH2004 protocols of the Histiocyte Society. RESULTS: The patients' ages at diagnosis ranged from one month to nine years. All patients had splenomegaly, fever, anemia, thrombocytopenia, hyperferritinemia and hypertriglyceridemia. Bone marrow hemophagocytosis was detected in six patients. In six cases, infectious diseases triggered the syndrome. In two cases, associated with visceral leishmaniasis, remission was achieved after treatment of the underlying infection. Three patients, who had Epstein-Barr-related hemophagocytic lymphohistiocytosis, required treatment with immunochemotherapy. They are alive and in remission; one patient had symptoms of juvenile rheumatoid arthritis and another, who was suspected of having primary hemophagocytic lymphohistiocytosis, entered into remission after bone marrow transplantation. Two deaths (28.6%) occurred in patients with suspected primary hemophagocytic lymphohistiocytosis; one whose clinical picture was triggered by cytomegalovirus infection did not respond to immunochemotherapy and the other died before any specific treatment was provided. CONCLUSION: As reported before, hemophagocytic lymphohistiocytosis has a multifaceted presentation with nonspecific signs and symptoms. In secondary forms, remission may be achieved by treating the underlying disease. In the primary forms, remission may be achieved with immunochemotherapy, but bone marrow transplantation is required for cure.

Cytogenetic abnormalities, WHO classification, and evolution of children and adolescents with acute myeloid leukemia

ABSTRACT Objectives: To describe cytogenetic and molecular abnormalities observed in children and adolescents with acute myeloid leukemia (AML), classify AML according to the World Health Organization (WHO) classifications from 2008 and 2016, and evaluate the prognosis according to clinical characteristics and cytogenetic abnormalities. Methods: A retrospective longitudinal study was performed on a population of 98 patients with AML, aged up to 16 years, seen in a single hospital from 2004 to 2015. Results: Among the 80 patients for whom it was possible to analyze the karyotype, 78.7% had chromosomal changes, the most frequent being t(15;17)(q22;q21). Of the 86 patients for whom we had cytogenetic or molecular data, making it possible to classify their AML according to the WHO classification, 52.3% belonged to the group with recurrent genetic abnormalities, 22% to the "AML not otherwise specified" group, 18.6% to the group with myelodysplasia-related cytogenetic changes, and 7% to the group with Down syndrome-related leukemia. Five-year overall survival (OS) for the whole group was 49.7% ± 5.2%. In the univariate and multivariate analyses, patients with myelodysplasia-related cytogenetic changes (OS 28.1% ± 12.2%) and those with "AML not otherwise specified" (OS 36.1% ± 11.2%) had an unfavorable prognosis when compared to patients with AML with recurrent genetic abnormalities (OS 71% ± 5.8%) and patients with Down syndrome-related AML (OS 83% ± 15.2%, p = 0.011). Conclusions: The results corroborate the importance of cytogenetic abnormalities as a prognostic factor and indicate the need for cooperative and prospective studies to evaluate the applicability of the WHO classification in the pediatric population.

Gene rearrangement study for minimal residual disease monitoring in children with acute lymphocytic leukemia.

OBJECTIVE: To detect markers for minimal residual disease monitoring based on conventional polymerase chain reaction for immunoglobulin, T-cell receptor rearrangements and the Sil-Tal1 deletion in patients with acute lymphocytic leukemia. METHODS: Fifty-nine children with acute lymphocytic leukemia from three institutions in Minas Gerais, Brazil, were prospectively studied. Clonal rearrangements were detected by polymerase chain reaction followed by homo/heteroduplex clonality analysis in DNA samples from diagnostic bone marrow. Follow-up samples were collected on Days 14 and 28-35 of the induction phase. The Kaplan-Meier and multivariate Cox methods were used for survival analysis. RESULTS: Immunoglobulin/T-cell receptor rearrangements were not detected in 5/55 children screened (9.0%). For precursor-B acute lymphocytic leukemia, the most frequent rearrangement was IgH (72.7%), then TCRG (61.4%), and TCRD and IgK (47.7%); for T-acute lymphocytic leukemia, TCRG (80.0%), and TCRD and Sil-Tal deletion (20.0%) were the most common. Minimal residual disease was detected in 35% of the cases on Day 14 and in 22.5% on Day 28-35. Minimal residual disease on Day 28-35, T-acute lymphocytic leukemia, and leukocyte count above 50 x 10(9)/L at diagnosis were bad prognostic factors for leukemia-free survival in univariate analysis. Relapse risk for minimal residual disease positive relative to minimal residual disease negative children was 8.5 times higher (95% confidence interval: 1.02-70.7). CONCLUSION: Immunoglobulin/T-cell receptor rearrangement frequencies were similar to those reported before. Minimal residual disease is an independent prognostic factor for leukemia-free survival, even when based on a non-quantitative technique, but longer follow-ups are needed.

Incidence and risk factors for central nervous system relapse in children and adolescents with acute lymphoblastic leukemia.

BACKGROUND: Despite all the advances in the treatment of childhood acute lymphoblastic leukemia, central nervous system relapse remains an important obstacle to curing these patients. This study analyzed the incidence of central nervous system relapse and the risk factors for its occurrence in children and adolescents with acute lymphoblastic leukemia. METHODS: This study has a retrospective cohort design. The studied population comprised 199 children and adolescents with a diagnosis of acute lymphoblastic leukemia followed up at Hospital das Clinicas, Universidade Federal de Minas Gerais (HC-UFMG) between March 2001 and August 2009 and submitted to the Grupo Brasileiro de Tratamento de Leucemia da Infância - acute lymphoblastic leukemia (GBTLI-LLA-99) treatment protocol. RESULTS: The estimated probabilities of overall survival and event free survival at 5 years were 69.5% (± 3.6%) and 58.8% (± 4.0%), respectively. The cumulative incidence of central nervous system (isolated or combined) relapse was 11.0% at 8 years. The estimated rate of isolated central nervous system relapse at 8 years was 6.8%. In patients with a blood leukocyte count at diagnosis ≥ 50 x 10(9)/L, the estimated rate of isolated or combined central nervous system relapse was higher than in the group with a count < 50 x 10(9)/L (p-value = 0.0008). There was no difference in cumulative central nervous system relapse (isolated or combined) for the other analyzed variables: immunophenotype, traumatic lumbar puncture, interval between diagnosis and first lumbar puncture and place where the procedure was performed. CONCLUSIONS: These results suggest that a leukocyte count > 50 x 10(9)/L at diagnosis seems to be a significant prognostic factor for a higher incidence of central nervous system relapse in childhood acute lymphoblastic leukemia.