Analysis of the immunophenotype of children treated on the Medical Research Council United Kingdom Acute Lymphoblastic Leukaemia Trial XI (MRC UKALLXI). Medical Research Council Childhood Leukaemia Working Party

Isolated Optic Nerve Relapse in a Pediatric Patient With T-Cell Lymphoblastic Leukemia: A Brief Report

Isolated optic nerve (ON) relapse is a rare occurrence in lymphoblastic leukemia (LBL). A 10-year-old boy with T-LBL presented 8 months after diagnosis with blurred vision and thickening of right ON on magnetic resonance imaging consistent with relapse. Cerebrospinal fluid and bone marrow were negative for leukemia. He received reinduction chemotherapy (including nelarabine and craniospinal radiation) followed by a myeloablative matched sibling donor bone marrow transplant. He remains in remission 2 years post-transplant with normal vision. We also review the literature for reports of isolated ON relapse in patients with LBL. Our patient's clinical course demonstrates that disease control can be achieved with early detection of ON relapse before disease progression.

Negative value of CD10-/CD34- immunophenotype in pediatric leukemia and development of a related cell line model for investigating drug resistance

PURPOSE

Appropriate sub-classification of leukemia according to the immunophenotypic characteristics of the malignant cells may improve therapeutic strategies. The aim of this study was to investigate the prognostic value of CD10/CD34 surface markers in pediatric acute lymphoblastic leukemia (pALL).

PATIENTS AND METHODS

A retrospective cohort study was performed in 79 children with ALL. Possible correlation between leukemia prognosis and CD10 CD34 immunophenotype was assessed using Kaplan-Meier and Cox regression analyses. A CD10- CD34- pre-B-ALL cell line was generated from a patient with resistant ALL. RN95 was characterized using light microscopy, immunophenotyping, karyotyping, and Western blotting. Drug sensitivity and resistant genes' expression profile were assessed using MTT and RT-PCR assays.

RESULTS

Kaplan-Meier analysis showed negative correlation between CD10/CD34 double negativity and patients' 2- and 5-year disease-free survival (DFS). Multivariate analysis indicated that the absence of CD10 and CD34 expression in the ALL patients was an independent negative prognostic marker for 2- and 5-year DFS. A novel cell line model, RN95, was developed with similar immunophenotype from a primary relapsed sample. Cells showed p53 positive functionality and demonstrated partial sensitivity to Vincristine, but complete resistance to Cytarabine. Overexpression of ABCB1, ABCA2, and ABCA3 was detected.

CONCLUSION

In the current study, simultaneous absence of CD10 and CD34 cell surface markers was introduced as an unfavorable prognostic factor in pediatric B-ALL. Moreover, a special cell line was established to help delineation of novel therapeutics for B-ALL drug resistance.

Evaluation of cost effective diagnostic tools in characterisation of Acute Leukemia in Southern India

The incidence of Acute Leukemia (AL) subtypes varies according to geographical distribution and more predominant in developing countries. The aim here was to evaluate the usefulness of cost effective diagnostic tools in characterization of Acute Lymphoblastic Leukemia (ALL) in resource poor population. One hundred and two AL cases were diagnosed. For diagnosis, cytochemical analysis and immunohistochemistry were performed. Among the children < 12 years, ALL was 64.3% while AML accounted for 30%. In patients > 12 years, ALL was 59.4% and AML was 31.3%. The B-ALL occurred most frequently than T-ALL in both the age groups while based on immunophenotyping in AML, CD13 was the most commonly expressed antigen. Hence, cost effective diagnostic tools namely the immunophenotyping and cytochemistry are useful and improve accuracy and rapidly risk-stratify patients that were diagnosed with acute leukemia.

Immunophenotypic, cytogenetic, and clinical features of 207 cases of childhood acute lymphoblastic leukemia in china

OBJECTIVE

In this study, we investigated the immunophenotypic subtype profiles of 207 Chinese children with acute lymphoblastic leukemia (ALL) and its association with cytogenetics and clinical features.

METHODS

A total of 207 children with ALL were immunophenotyped by 4-color flow cytometry using a panel of monoclonal antibodies. Among the 207 patients enrolled in this study, 146 cases were also subjected to karyotype analysis by R-banding technology.

RESULTS

Of the 207 children with ALL, 11.6% were identified as T-ALL and 88.4% as B-ALL. Among B-ALL, 6.6% were identified as Pro-B ALL, 67.2% as Com-B ALL, 24.0% as Pre-B ALL, and 2.2% as mature-B ALL. Myeloid antigen (MyAg) expression was documented in 42.5% of the 207 cases analyzed and CD13 was the most commonly expressed MyAg (31.4%). No difference was observed in the expression of MyAg between the groups of patients with T-ALL (41.7%) and B-ALL (42.6%). Abnormal karyotypes were detected in 84 of 146 (57.5%) children. The clinical and biological characteristics of ALL patients between the MyAg⁺ and MyAg⁻ groups showed that a higher percentage of patients with high WBC count (>50×10⁹/L) and higher CD34 positivity were found to be correlated with MyAg⁺ ALL.

CONCLUSIONS

Our results indicate that the distribution of ALL in Chinese children was similar to the general distribution pattern in other countries. Unlike previous studies, we found that the expression of MyAg in children with T-ALL and B-ALL was comparable, and the percentage of patients with a high WBC count (>50×10⁹/L) and CD34 positivity in MyAg⁺ was higher than that in MyAg⁻ ALL types, but no differences were found with regard to other clinical features.

BCR-ABL Translocation in Pediatric Acute Lymphoblastic Leukemia in Southern India

Cytogenetics and polymerase chain reaction (PCR) based assays provide important information regarding biologically defined and prognostically relevant subgroups in acute leukemias. We utilized karyotyping and molecular analysis by reverse transcriptase PCR for the BCR-ABL translocation, in addition to morphological study, cytochemistry and immunophenotyping, to study 24 cases of pediatric acute lymphoblastic leukemia (ALL). Our objective was to determine the frequency of the BCRABL translocation in childhood ALL from southern India. Karyotyping showed one case of hyperdiploidy, one case of t (12; 21) translocation and one case of 46, XY-21+mar. The BCR-ABL translocation was found in 8.3% of these cases. One of these was a cryptic translocation, the karyotype being normal. BCR-ABL positivity in ALL is associated with aggressive disease and has been shown to be a poor prognostic factor, especially in children.

Long-term follow-up of the United Kingdom medical research council protocols for childhood acute lymphoblastic leukaemia, 1980-2001

Between 1980 and 2001, the United Kingdom Medical Research Council Childhood Leukemia Working Party has conducted 4 clinical trial in acute lymphoblastic leukemia, which have recruited a total of 6516 patients. UKALL VIII examined the role of daunorubicin in induction chemotherapy, and UKALL X examined the role of post-induction intensification. Both resulted in major improvement in the outcomes. UKALL XI examined the efficacy of different methods of CNS-directed therapy and the effects of an additional intensification. ALL97, which was initially based on the UKALL X D template (two intensification phases), examined the role of different steroids in induction and different thiopurines through continuing chemotherapy. A reappraisal of results from UKALL XI compared to other cooperative group results led to a redesign in 1999, which subsequently resulted in a major improvement in outcomes. Additionally, ALL97 and 97/99 demonstrated a significant advantage for the use of dexamethasone rather than prednisolone; although the use of 6-thioguanine resulted in fewer relapses, this advantage was offset by an increased incidence of deaths in remission. Over the era encompassed by these four trials there has been a major improvement in both event-free and overall survival for children in the UK with ALL.

Characterization of acute lymphoblastic leukemia subtypes in moroccan children

We present the incidence and the immunologic characteristics of acute lymphoblastic leukemia (ALL) subsets in Moroccan children. We studied 279 unselected patients below the age of 18 years with newly diagnosed ALL. Cases were classified according to immunophenotype: 216 (77.42%) precursor B-cell phenotype (pB-cell), mature B-cell in 4 (1.43%), and T-cell in 59 (21.15%) cases. The subclassification using the CD10 antibody revealed 197 cases pB-ALL CD10+ (91.2%) and 9 cases T-ALL CD10+ (19.2%). The age distribution showed a peak in incidence between 3 and 5 years among the pB-cell ALLs subtype. There was a significantly higher frequency of males in the T-ALL subset (M/F ratio: 2.93 : 1) and more females in the T-ALL CD10+ subset when compared with the T-ALL CD10- subset. All tested pB-cell-lineage ALLs expressed CD19, CD79a, and surface CD22, terminal deoxynucleotidyl transferase (TdT) was detectable in 89.9% of cases, and cells in 74.1% of cases express CD34. All tested T-lineage ALL cells have surface CD7 and cytoplasmic CD3 (cCD3) antigens, CD5 was found in 98.2% cases, and 70.5% express TdT. CD1a, surface CD3 (sCD3), and CD4 are detected in more than 80% of cases; this frequency is higher than the 45% generally observed. Myeloid antigens occur more frequently and were expressed in 124 (57.4%) of pB-cell-ALL cases and 20 (33.9%) of T-cell ALL cases. Our results show that the distribution of ALLs in Moroccan children is similar with the general distribution pattern in developed countries except for the high frequency of T-ALL phenotype. The phenotypic profiles of our patients are close to those reported in literature for B-lineage ALLs; for the T-cell ALL subgroup, the blast cells express more CD1a, surface CD3, and CD4 while expressing less TdT. The high frequency of CD1a expression resulted in an excess of the common thymocyte subtype.

CD10 AND CD34 expression in childhood acute lymphoblastic leukemia in Morocco: clinical relevance and outcome

CD10 and CD34 expression in 86 Moroccan children with acute lymphoblastic leukemias (ALL) and the relevance to prognosis, diagnosis, and outcome during a 5-year follow-up were examined. At diagnosis, 57% of patients had CD10(+) blasts, while 35% had CD34(+) blasts. The CD10(+) blast frequency was much higher (80%) in B-ALL than in T-ALL (20%). The frequency of CD34(+) blasts was higher in B-ALL (48%) compared to T-ALL (16%). The 5-year survival curves showed that children with CD10(+) B-ALL had a significantly longer survival rate than those with CD10(-), as observed for T-ALL. The survival rate of B-ALL expressing CD34 was higher than that of CD34(-). Thus, CD34 and CD10 expression may have prognostic value and is associated with a better clinical outcome.

The age incidence of childhood B-cell precursor acute lymphoblastic leukemia in Mexico City

The objective of this population-based survey was to assess the peak age of incidence of B-cell precursor acute lymphoblastic leukemia (ALL) in children in Mexico City (MC). All patients were classified according to their immunophenotype, and only B-cell precursor and T-lineage were analyzed. Rates of incidence were calculated x10 children. Of the 364 children from MC who were included in this study, immunophenotyping had been performed for 81.6%. The frequency of B-cell precursor ALL was 76.1%, whereas T lineage ALL showed a frequency of 23.6%. Peak age for ALL was 2 to 3 years of age. B-cell precursor ALL was the major contributor to peak age; T lineage ALL showed a peak among 1 and 3 years of age. We conclude that the age peak for children with ALL in MC is within the ranges reported for developed countries and that B-cell precursor ALL is the main contributor to these peak.

Successful treatment without cranial radiotherapy of children receiving intensified chemotherapy for acute lymphoblastic leukaemia: results of the risk-stratified randomized central nervous system treatment trial MRC UKALL XI (ISRC TN 16757172)

Concern about late adverse effects of cranial radiotherapy (XRT) has led to alternative approaches to eliminate leukaemia from the central nervous system (CNS) in childhood acute lymphoblastic leukaemia (ALL). The Medical Research Council UKALL XI trial recruited 2090 children with ALL between 1990 and 1997. Median follow-up is 7 years 9 months; event-free survival (EFS) and overall survival were 63.1% and 84.6%, respectively, at 5 years and 59.8% and 79.4% at 10 years. The isolated CNS relapse rate was 7.0% at 10 years. Patients were randomized for CNS-directed therapy within white blood cell (WBC) groups. For WBC <50 x 10(9)/l, high-dose intravenous methotrexate (HDMTX) (6-8 g/m2) with intrathecal methotrexate (ITMTX) was compared with ITMTX alone, and was significantly better at preventing isolated and combined CNS relapse, but non-CNS relapses were similar. There was no significant difference in EFS at 10 years, 64.1% [95% confidence interval (CI) 60.4-67.8] with HDMTX plus ITMTX, and 63.0% (95% CI 59.5-66.5) with ITMTX alone. For WBC >/=50 x 10(9)/l, HDMTX with ITMTX was compared with XRT and a short course of ITMTX. CNS relapses were significantly fewer with XRT, but there was a non-significant increase in non-CNS relapses. EFS was not significantly different, being 55.2% (95% CI 47.8-62.6) at 10 years with XRT and 52.1% (95% CI 44.8-59.4) with HDMTX plus ITMTX.

Prognosis in childhood and adult acute lymphoblastic leukaemia: a question of maturation?

Acute lymphoblastic leukaemia (ALL) is a disease diagnosed in children as well as adults. Progress in the treatment of ALL has led to better survival rates, however, children have benefited more from improved treatment modalities than adults. Recent evidence has underscored that the difference in characteristics and biology of adult versus childhood ALL might be the result of a different origin. According to the two-hit paradigm of Knudson, to develop cancer two genetic events are necessary. It has been suggested, that in childhood ALL the first genetic event happens in the more mature lymphoid committed progenitor cells, whereas in adult ALL the first hit occurs in multipotent stem cells. This review compares patient characteristics, the extent of the disease, leukaemic cell characteristics and treatment between childhood and adult ALL. This is discussed in relation to the hypothesis that the maturation stage of the cells, from which the leukaemia arises, is responsible for the differential behaviour of adult and childhood ALL.

The prognostic significance of antigen expression in leukaemia

Numerous immunophenotypic features have been examined for their potential prognostic significance in predicting treatment outcome in leukaemias. These include immunophenotypic subgroups of acute lymphoblastic leukaemia (ALL) and immature acute myeloid leukaemia, expression of individual surface antigens or combined immunophenotypic features, and more recently, molecules mediating the multidrug resistance phenotype or being involved in the regulation of drug-induced apoptosis. Most previous studies investigating the prognostic significance of antigen expression in leukaemia have not used the information provided by multiparameter flow cytometry and have chosen rather arbitrary cut-off points for marker positivity. Moreover, given significant associations between immunophenotypic features and genetic abnormalities in leukaemic cells, immunophenotyping as an independent predictor of treatment outcome has been questioned. Thus, except for lineage assignment of leukaemic blasts and definition of maturational status in ALL, information provided by immunophenotyping is currently not applied to risk-classification systems or used for planning patient treatment in leukaemia. We review some of the recent findings regarding the prognostic impact of distinct immunophenotypic features in acute leukaemias and myelodysplastic syndrome.

Complex karyotypes in childhood acute lymphoblastic leukemia: cytogenetic and molecular cytogenetic study of 21 cases

Cytogenetic and molecular cytogenetic analysis of 79 childhood acute lymphoblastic leukemias (ALL) revealed chromosomal abnormalities in 76 (96%). Complex karyotypes (a finding of three and more chromosomal aberrations in a karyotype) were identified in 21 (26.6%) out of 79 patients. In 11 patients, complex karyotypes have included common recurrent chromosomal abnormalities, such as translocation t(12;21) in seven cases, t(9;22) in two cases, one case with t(2;1;19) and another one with translocation involving 11q23. In 10 patients, miscellaneous abnormalities were detected. Five patients displayed hyperdiploidy (47 approximately 57 chromosomes), three patients complex karyotypes with deletions of 9p, one patient with two new complex translocations t(2;4;12;13) and t(7;11;20), and the last patient with dic(12;21). The evaluation of the frequency of the chromosomal breaks (>5 per chromosome) showed that chromosomes 2, 4, 5, 7, 9, 12, 13, and 21 were most frequently affected. Survival analysis revealed statistically significant unfavorable event-free survival (EFS) (P=0.013) and decreased overall survival in the group with complex karyotypes (n=21) compared with the other cases (n=58). The evaluation of overexpression profile revealed increased occurrence of double CD13/CD33 positivity in patients with common recurrent chromosomal abnormalities (in 70% of cases); no such cases were registered in the other group (P<0.01).

Direct association of socio-economic status with T-cell acute lymphoblastic leukaemia in children

Lymphoblasts from 186 consecutive untreated children <18 years were analysed by flow cytometry in Brazil. Socio-economic status was defined by family income; undernourishment by height and weight for age standardised z scores below -1.28. The observed frequencies were precursor-B (pre-B) CD10 positive acute lymphoblastic leukaemia (ALL) (CD10+) 65%, pre-B CD10 negative (CD10-) 13%, and T-ALL 18%. The typical incidence peak at age 2-5 years was observed among the CD10 positive cases. Nutritional variables were not associated with immunophenotypes. Low monthly per capita income was associated with T-immunophenotype (P=0.024). In conclusion, a direct association between unfavourable socio-economic status and the T-phenotype indicates a potential role of socio-economic factors on the genesis of ALL in children, thus confirming indirect data of the international literature.

Constitutional sequence variation in the Fanconi anaemia group C (FANCC) gene in childhood acute myeloid leukaemia

The extent to which genetic susceptibility contributes to the causation of childhood acute myeloid leukaemia (AML) is not known. The inherited bone marrow failure disorder Fanconi anaemia (FA) carries a substantially increased risk of AML, raising the possibility that constitutional variation in the FA (FANC) genes is involved in the aetiology of childhood AML. We have screened genomic DNA extracted from remission blood samples of 97 children with sporadic AML and 91 children with sporadic acute lymphoblastic leukaemia (ALL), together with 104 cord blood DNA samples from newborn children, for variations in the Fanconi anaemia group C (FANCC) gene. We found no evidence of known FANCC pathogenic mutations in children with AML, ALL or in the cord blood samples. However, we detected 12 different FANCC sequence variants, of which five were novel to this study. Among six FANCC variants leading to amino-acid substitutions, one (S26F) was present at a fourfold greater frequency in children with AML than in the cord blood samples (odds ratio: 4.09, P = 0.047; 95% confidence interval 1.08-15.54). Our results thus do not exclude the possibility that this polymorphic variant contributes to the risk of a small proportion of childhood AML.

Acute lymphoblastic leukaemia: diagnosis and classification

Acute lymphoblastic leukaemia (ALL) is a heterogeneous disease with distinct biological and prognostic groupings. Diagnosis relies on traditional cytomorphological and immunohistochemical evaluation of the leukaemic blasts. Subsequently, cytogenetic analysis identifies clonal numeric and/or structural chromosomal abnormalities that may be present, thus confirming the subtype classification and providing important prognostic information for treatment planning. The major chromosomal abnormalities in ALL are t(9;22)(q34;q11), t(12;21)(p13;q22), t(4;11)(q21;q23), t(1;19)(q23;p13), 8q24 translocations and hyperdiploidy. Generally, hyperdiploidy, occurring most frequently in paediatric cases, is associated with a good prognosis, while hypodiploidy confers a poor prognosis. Among structural chromosomal abnormalities, the t(9;22)(q34;q11) resulting in the BCR/ABL fusion protein, and rearrangements of the MLL gene, confer a poor prognosis in both children and adults, while t(12;21)(p13;q22), resulting in the TEL/AML1 fusion protein, and del (12p) confer a good prognosis. More recently, additional diagnostic and prognostic information has been gained from fluorescence in situ hybridization (FISH) and DNA microarray techniques.

Failure of a new protocol to improve treatment results in paediatric lymphoblastic leukaemia: lessons from the UK Medical Research Council trials UKALL X and UKALL XI

The impact of various types of intensification therapy was examined in a cohort of 3617 children aged 1-14 years with acute lymphoblastic leukaemia (ALL) enrolled in the Medical Research Council (MRC) UKALL X (1985-90) and UKALL XI (1990-97) trials. UKALL XI was modified in 1992 to incorporate the "best arm" of UKALL X with two 5-d intensification blocks at 5 and 20 weeks, and an additional randomization in respect of a third intensification at 35 weeks but omission of two consecutive injections of daunorubicin during induction. All children were eligible for randomization irrespective of risk group. The impact of the various types of intensification therapy was examined in a stratified analysis. At a median follow up of 102 months, both trials had an identical event-free survival of 61% (95% CI 58-63%) at 8 years. Survival at 8 years in UKALL XI was significantly better in than in UKALL X, 81% (79-83%) compared with 74% (72-76%) (P = < 0.001), owing to improved management of relapse. There was a highly significant trend in reduction of the number of relapses and deaths with increased intensity of therapy both for children with initial leucocyte count < 50 x 10(9)/l (P = < 0.001) and > or = 50 x 10(9)/l (P = 0.002). Introduction of a third late intensification block compensated for omission of anthracyclines during induction but produced little additional benefit. These results show, in a large cohort of patients, that minor modifications of therapy may influence relapse rate and obviate the benefit of previous randomized trials. The failure to adapt treatment for higher risk children contributed to these disappointing results.

Treatment of infants with lymphoblastic leukaemia: results of the UK Infant Protocols 1987-1999

One hundred and twenty-six infants with acute lymphoblastic leukaemia (ALL) were treated on two consecutive protocols, Infant 87 (n = 40) and Infant 92 (n = 86), in an attempt to improve the poor prognosis of this disease. Both included intensive induction and consolidation with intrathecal and high-dose systemic therapy for central nervous system (CNS) protection. Intensification therapy was modified and high-dose chemotherapy with bone marrow transplantation in first remission was permitted in Infant 92. Four-year event-free survival was superior in Infant 92 (33%; 95% CI 23-44%) compared with Infant 87 (22.5%; 95% CI 12-37%) (P = 0.04) and survival at 4 years was also superior, 46% (95% CI 35-57%) c.f. 32.5% (95% CI 20-48%) (P = 0.01), largely as a result of a significant reduction in remission deaths. Twelve patients in Infant 92 underwent bone marrow transplantation (BMT) in first remission, but their survival was no better than that of patients receiving chemotherapy. Multivariate analysis of prognostic factors showed the adverse influence of younger age, CNS involvement at diagnosis and a high initial leucocyte count, but not of CD10 expression. Cytogenetic analysis, available in 93% of patients in Infant 92, showed that 67% had chromosomal rearrangements involving 11q23 of which 39% had the translocation t(4;11) (q21;q23). There was no significant difference in event-free survival between cytogenetic subgroups, although no children under 6 months of age with 11q23 abnormalities, other than the t(4;11), survived. In conclusion, infants with lymphoblastic leukaemia remain a high-risk group, but it is unclear whether their adverse prognosis can be attributed to unfavourable cytogenetics alone. The role of high-dose therapy and BMT in first remission remains uncertain.

Clinical features, cytogenetics and outcome in acute lymphoblastic and myeloid leukaemia of infancy: report from the MRC Childhood Leukaemia working party

The clinical features, cytogenetics and response to treatment have been examined in 180 infants (aged <1 year) with acute leukaemia; 118 with acute lymphoblastic leukaemia (ALL) and 62 with acute myeloid leukaemia (AML). Comparison of clinical features showed no difference in age or sex distribution between infants with ALL and AML but infants with ALL tended to have higher leucocyte counts at presentation. Cytogenetic abnormalities involving 11q23 were found in 66% of ALL and 35% of AML cases, the commonest, t(4;11) being found only in ALL. The other recognised 11q23 translocations were found in both types of leukaemia. Few patients had the common cytogenetic abnormalities associated with ALL in older children and few with AML had good risk abnormalities. Four year event-free survival 60% cf 30% (P = 0.001) and survival 65% cf 41% (P = 0.007) were significantly better in AML than ALL. These results were due to a lower risk of relapse 27% cf 62% at four years. Superior event-free survival was also seen in the subgroup of patients with 11q23 abnormalities and AML (55% cf 23%). The reasons for superior response in AML are unknown but may be related to the intensity of treatment, lineage of the leukaemia or other as yet unidentified factors.

Down's syndrome and acute lymphoblastic leukaemia: clinical features and response to treatment

AIMS

To examine the clinical and biological features of acute lymphoblastic leukaemia in children with Down's syndrome (DS), to compare their survival with other children, and to determine if entry to trials and survival has improved.

METHODS

Examination of presenting features and response to treatment in patients treated in two consecutive national trials, MRC UKALL X and XI.

RESULTS

The proportion of children with DS was significantly higher in UKALL XI (1.9%) than UKALL X (0.9%). Children with DS tended to be under 10 years and to have the common ALL subtype. Cytogenetic analysis showed that favourable features, such as high hyperdiploidy and t(12;21) were less frequent but also that there was a lack of translocations associated with a poor prognosis. Children with DS showed no increase in risk of relapse at any site but their survival and event free survival were inferior to other children. These results were caused by an increased number of infective deaths during remission (11% compared to 2%). At five years overall survival was 73% in DS children compared with 82% in other children; event free survival was 53% compared to 63% in non-DS children.

CONCLUSIONS

Entry of children with DS to national trials has increased and survival has improved. However they remain at risk of relapse and also of treatment related mortality. These findings emphasise the need for both intensive chemotherapy and optimal supportive care.

Determinants of outcome after intensified therapy of childhood lymphoblastic leukaemia: results from Medical Research Council United Kingdom acute lymphoblastic leukaemia XI protocol

The single most important prognostic determinant in childhood acute lymphoblastic leukaemia (ALL) is effective therapy and changes in therapy may influence the significance of other risk factors. The effect of intensified therapy on the importance of currently recognized phenotypic and genotypic determinants of outcome was assessed in 2090 children enrolled on the Medical Research Council United Kingdom acute lymphoblastic leukaemia XI (MRC UKALL XI) protocol. Treatment allocation was not determined by risk factors. Multivariate analysis confirmed the dominant influence on prognosis of age, sex and presenting white cell count (WCC). After allowing for these features, blast karyotype, d 8 marrow blast percentage and remission status at the end of induction therapy were the only remaining significant predictors of outcome. Organomegaly, haemoglobin concentration, French--American--British type, body mass index, presence of central nervous system disease at diagnosis, immunophenotype and presence of TEL/AML1 fusion gene (examined in a subset of 659 patients) either had no significant effect on outcome or were significant only in univariate analysis. Among karyotype abnormalities with an independent influence on prognosis, high hyperdiploidy (> 50 chromosomes) was shown to be favourable, whereas near haploidy (23--29 chromosomes), presence of the Philadelphia chromosome, t(4;11) and abnormalities affecting the short arm of chromosome 9 [abn (9p)] were adverse risk factors. Early responders to therapy, determined by residual marrow infiltration after 8 d of induction therapy, had a good outcome, while the small proportion of patients who did not achieve a complete remission by the end of induction therapy had a poor outcome. A third block of late intensification was shown to improve event-free survival by 8% at 5 years. The effect of these risk factors was not significantly different between those randomized to the third intensification block and those not randomized to a third block.

Long-term follow-up of the United Kingdom Medical Research Council protocols for childhood acute lymphoblastic leukaemia, 1980-1997. Medical Research Council Childhood Leukaemia Working Party

Results of three consecutive completed UK trials (1980-1997) for childhood lymphoblastic leukaemia are presented. National accrual has progressively increased so that over 90% of all the country's ALL cases were treated on the latest trial reported, UKALLXI. From 1980 to 1990, event-free and overall survival progressively improved, following adoption of an American therapy template and use of two post-remission intensification modules. Since 1990 despite demonstration of the benefit of a third intensification module overall event-free survival (EFS) has not improved further. Survival remains high due to a good retrieval rate especially for those relapsing off treatment after receipt of two intensification pulses. Possible reasons for the plateau in event-free survival (including type and dose of induction steroid, dropping of induction anthracycline, type and dose of asparaginase, gaps early in therapy following intensification, and overall lack of compliance in maintenance) are being explored in the latest protocol ALL '97. Cranial irradiation had been successfully replaced by a long course of intrathecal methotrexate injections for the majority of patients. Age (<1 year >10 years) sex (male) and white count >50 x 10(9)/l plus slow initial bone marrow clearance were consistently the most important independent prognostic indicators during this time period. Rome/NCI criteria accurately predict standard and high-risk groups for B cell lineage, but not consistently for T cell disease. This international collaborative venture might help us to define those truly at highest risk, and how we can optimise therapy for specific subgroups including T-ALL and those with unfavourable cytogenetics.

The United Kingdom Childhood Cancer Study: objectives, materials and methods. UK Childhood Cancer Study Investigators

An investigation into the possible causes of childhood cancer has been carried out throughout England, Scotland and Wales over the period 1991-1998. All children known to be suffering from one or other type of the disease over periods of 4-5 years have been included, and control children matched for sex, age and area of residence have been selected at random from population registers. Information about both groups of children (with and without cancer) has been obtained from parental questionnaires, general practitioners' and hospital records, and from measurement of the extent of exposure to radon gas, terrestrial gamma radiation, and electric and magnetic fields. Samples of blood have also been obtained from the affected children and their parents and stored. Altogether 3,838 children with cancer, including 1,736 with leukaemia, and 7,629 unaffected children have been studied. Detailed accounts are given of the nature of the information obtained in sections describing the general methodology of the study, the measurement of exposure to ionizing and non-ionizing radiation, the classification of solid tumours and leukaemias, and the biological material available for genetic analysis.

Acute lymphoblastic leukemia in children

As the overall long-term event-free survival rate in children with acute lymphoblastic leukemia approaches 80%, emphasis is being placed on risk-directed therapy so that patients are neither overtreated nor undertreated. It has become apparent that a risk assignment system based on primary genetic abnormalities is inadequate by itself. For example, leukemias with the MLL-AF4 or BCR-ABL fusion gene are, in fact, heterogeneous diseases. Many require allogeneic hematopoietic stem-cell transplantation; some, if the patient is of favorable age and has a low presenting leukocyte count, can be cured with chemotherapy alone. Measurement of early responses to therapy and extent of minimal residual disease can greatly improve the accuracy of risk assessment. Consideration of the variable effects of therapy on the prognostic significance of specific genetic abnormalities is also important. Therefore, TEL-AML1 fusion confers a favorable prognosis in some protocols of chemotherapy but not in others. Studies to identify genetic polymorphisms with pharmacokinetic and pharmacodynamic significance promise to guide further refinement of treatment strategies. This will allow maximization of anticancer effects without induction of unacceptable toxicity in individual patients.

Aberrant immunophenotypes detected by flow cytometry in acute lymphoblastic leukemia

The present study was designed to analyse the proportion of ALL patients in which the phenotypic detection of minimal residual disease (MRD) is feasible, based on the presence of aberrant phenotypes: lineage infidelity, asynchronous expression, overexpression and ectopic phenotype. For this purpose we have prospectively investigated the phenotype of blast cells from 25 patients at diagnosis using a large panel of monoclonal antibodies by multiparametric flow cytometry. The mean age was 23.3 +/- 17.3 with 10 children and 15 adults. 14 patients were classified as L1, 9 L2 and 2 L3 according to the FAB classification. 17 cases were B-lineage ALL and 8 T-ALL. 23 out of 25 cases (92%) included in this study displayed phenotypic aberrations at diagnosis (15 out of 17 cases of B-lineage ALL and all T-ALL patients). 76% of patients displayed two or more than two aberrancies. The phenotypic aberrations were lineage infidelity, found in 12 patients, asynchronous antigen expression detected in 17 patients, antigen overexpression in 4 patients and ectopic phenotype in 7 patients. In summary our results show that when a large panel of MoAbs is used for the immunophenotypical characterization of ALL, most patients display aberrant phenotypes, the coexistence of more than two aberrant antigen expressions being frequently detected. These results suggest that the use of immunological methods for the detection of MRD in ALL based on the existence of aberrant phenotypes could be of great help for the follow-up of patients in complete remission.

Patterns of care and survival for children with acute lymphoblastic leukaemia diagnosed between 1980 and 1994

AIMS

To document survival rates after acute lymphoblastic leukaemia (ALL) during the era of modern chemotherapy, to assess effects of prognostic factors at presentation, and to investigate the relation of survival to patterns of organisation of care.

PATIENTS

From a population based series of 5078 children diagnosed in the UK during 1980-94, 4988 remained for analysis after exclusion of nine children ascertained from death certificates alone and 81 who received no antileukaemia treatment.

MAIN OUTCOME MEASURES

Actuarial survival rates.

RESULTS

Between 1980-84 and 1990-94, the proportion of children treated at paediatric oncology centres rose from 77% to 89%, and the proportion entered into national trials rose from 59% to 82%. Each of age, sex, white blood count, immunophenotype, and Down's syndrome status had a highly significant effect on survival. Five year survival improved from 67% in 1980-84 to 81% in 1990-94, a 42% reduction in the risk of death within five years of diagnosis. Survival did not differ significantly between hospitals with different numbers of new patients per year or between paediatric oncology centres and other hospitals. Children who were entered into national trials had higher survival and this difference became greater in recent years; five year survival rates for children diagnosed during 1980-84 were 70% and 64% for trial and non-trial patients, respectively; in 1990-94 the rates were 84% and 68% for trial and non-trial patients, respectively.

CONCLUSIONS

Survival after ALL continues to improve. Nearly 50 children/year diagnosed during 1990-94 survived who would have died a decade before. Survival does not vary systematically with place of treatment but is higher for children entered into national trials.