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To determine whether skin puncture blood can be used reliably for CD4 lymphocyte counts, the numbers of the major subsets of lymphocytes were assessed in paired venous and skin puncture blood samples from 22 children and 10 adults. Paired values were highly correlated, with skin puncture values being about 7% higher than venous values for each cell type. Differences were of borderline statistical significance for total lymphocytes and for each subset except CD3+ CD8+ T lymphocytes. Nevertheless, the magnitude of the differences was small and unlikely to be of clinical importance, and it seems that skin puncture samples may be preferable for CD4 counts in children or adults with difficult venous access. [ABSTRACT FROM PUBLISHER]

A study was carried out to determine the frequency of combined iron deficiency and beta-thalassaemia trait in a cohort of British Asian children to see whether the trait protects iron status. Of 470 consecutive children with red cell microcytosis, 77 had beta-thalassaemia trait and 26 (34%) of these also had evidence of iron deficiency. It was most common and profound in children under five years of age where the prevalence was 16 in 33 (48.5%). This suggests that iron deficiency is no less common in Asian children with beta-thalassaemia trait than in those without. It should not be presumed that the trait protects iron status or that the two are in any way mutually exclusive, at least in the early years. [ABSTRACT FROM PUBLISHER]

A nationwide study of intracellular drug metabolite concentrations in children prescribed 6-mercaptopurine for the treatment of lymphoblastic leukaemia was carried out to assess interpatient variability at a standardised dose. Nine children (2% of the total) had completely undetectable metabolites, indicative of non-compliance. Five were adolescents, but otherwise they had no obvious distinguishing characteristics. Not taking any 6-mercaptopurine at all is uncommon, but the problem cannot be predicted. The total number of children who do not comply cannot be determined from this study, but the nine children described represent only a fraction of these. [ABSTRACT FROM AUTHOR]

Books: Practical Patient Safety Paediatric Exercise Science and Medicine (2nd edn) Asthma and COPD: Basic Mechanisms and Clinical Management (2nd edn). [ABSTRACT FROM AUTHOR]

The article comments on the arguments of doctors Angus J. Dawson and Steve M. Yentis on the obligation of British research ethics committees (RECs) to consider the science of research applications because it is related with ethics. It states that RECs must rely on scientific appraisals performed by others to ensure that a study underwent adequate review. It mentions the proposal for a national network of independent research ethics advisers for the National Research Ethics Service (NRES).

1. The aim of this study was to investigate 6-mercaptopurine (6MP) metabolism by human liver cytosol in vitro. 2. Cytosol was prepared from seven human livers (A-G). A single cytosol (C) was used to optimize incubation conditions. 3. Cytosols A-G were incubated with 6MP at 2, 10 and 500 muM for two fixed times (5 and 48 h). Parent drug, thiopurine and thionucleotide metabolites were quantitated by high performance liquid chromatography at all time points. 4. At 5 and 48 h the 2 muM and 10 muM 6MP incubations contained both 6MP and its initial nucleotide metabolite, thioinosine 5'-monophosphate (TIMP). In addition, the 10 muM 6MP 48 h incubates contained small amounts of 6-thioguanine (6TG, median 0.12 muM). At 500 muM 6MP all seven liver incubates produced a range of metabolites. At 48 h these included thiouric acid, 8-hydroxy-6-mercaptopurine and 6-methylmercaptopurine (median 31, 19.5 and 8.8 muM respectively), with TIMP, 6TG, thioxanthine and thioxanthine nucleotide at median concentrations of 61, 0.79, 2.11 and 0.80 muM respectively. Thioguanine nucleotides, major metabolites measured in vivo, were not detected. 5. These results indicate that the human liver 6MP metabolic profile is dependent upon drug concentration. [ABSTRACT FROM AUTHOR]

Corticosteroids are an essential component of treatment for acute lymphoblastic leukaemia (ALL). Prednisolone is the most commonly used steroid, particularly in the maintenance phase of therapy. There is increasing evidence that, even in equipotent dosage for glucocorticoid effect, dexamethasone has enhanced lymphoblast cytotoxicity and penetration of the central nervous system (CNS) compared with prednisolone. Substitution of dexamethasone for prednisolone in the treatment of ALL might, therefore, result in improved event-free and overall survival. Children with newly diagnosed ALL were randomly assigned to receive either dexamethasone or prednisolone in the induction, consolidation (all received dexamethasone in intensification) and continuation phases of treatment. Among 1603 eligible randomized patients, those receiving dexamethasone had half the risk of isolated CNS relapse ( P = 0·0007). Event-free survival was significantly improved with dexamethasone (84·2% vs. 75·6% at 5 years; P = 0·01), with no evidence of differing effects in any subgroup of patients. The use of 6·5 mg/m2 dexamethasone throughout treatment for ALL led to a significant decrease in the risk of relapse for all risk-groups of patients and, despite the increased toxicity, should now be regarded as part of standard therapy for childhood ALL. [ABSTRACT FROM AUTHOR]

Aims Since relatively little is known about the pharmacokinetics of 6-thioguanine (6TG) in children receiving 6-thioguanine for maintenance therapy of acute lymphoblastic leukaemia (ALL), we studied plasma drug concentrations under standardized conditions and investigated the effect of food on parent drug pharmacokinetics and the accumulation of the active metabolites 6-thioguanine nucleotides (6-TGNs) in red cells. Methods Single oral doses of 40 mg of 6-TG were administered both in the fasting and fed state to children with ALL. Pharmacokinetic sampling was performed up to 6 h post dose. Daily oral doses of 40 mg m-2 of 6-TG were administered both fasting and after food over two 4 week periods. Twice weekly samples were taken for metabolite concentrations. The study design was cross-over with each child receiving dosing in either fasted or after food over a 4 week period in each phase. Results Eleven patients were studied. A wide interindividual variation in Cmax (median 313 pmol ml-1, range 51–737) and AUC (median 586 pmol ml-1 h, range 156–1306) was observed in the fasted state. Concomitant food administration resulted in a significant reduction in Cmax (median 71 vs 313 pmol ml-1, P = 0.006, CI from 36 to 426), AUC (median 200 vs 586 pmol ml-1 h, P = 0.006, 95% CI from 109 to 692), and time to reach Cmax (median 1.5 vs 3 h, P = 0.013, 95% CI from 0.74 to 2.73). There was no difference in the steady state concentration of red cell 6-TGNs observed after a 4 week period of 6-TG administered fasting or after food. Conclusions Children with ALL demonstrate significant interindividual variation in 6-TG pharmacokinetics. Although there would appear to be a reduction in parent drug Cmax and AUC with food there was no difference in 6-TGN concentrations after 4 weeks of 6-TG. Taking the drug on an empty stomach may not be necessary. [ABSTRACT FROM AUTHOR]

In the last 20 years, the survival rate for children with acute lymphoblastic leukaemia (ALL) has markedly improved, largely owing to a decrease in relapses. However, children still die from complications of treatment and these are potentially preventable. We have analysed data from three large consecutive national protocols for ALL from 1980 to 1997 [Medical Research Council United Kingdom ALL (MRC UKALL) trials VIII, X and XI] to compare the incidence and causes of treatment-related deaths (TRD). The percentage of TRD has fallen from 9% to 2% (UKALL VIII to XI), largely as a result of a decrease in fatal infections. Deaths during induction have fallen from 3% to 1%, the main causes of death being bacterial, followed by fungal infection, while other causes, chiefly haemorrhage, have not declined. Remission deaths also decreased from 6% to 1%, particularly those deaths due to measles and pneumocystis carinii. More guidelines for surveillance and treatment of infections have been included within progressively more intensive protocols. Risk factor analysis showed increased TRD in patients with Down's syndrome, high leucocyte count and older age in UKALL XI. In contrast, the introduction of blocks of intensification was not associated with an increased death rate. While improved supportive care has reduced the incidence of TRD, there is still scope for further reduction by prompt treatment of suspected infection. Maintenance of herd immunity remains of vital importance in avoiding deaths from measles. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Treatment of children with acute lymphoblastic leukaemia (ALL) aims to cure all patients with as little toxicity as possible and, if possible, to restrict further intensification of chemotherapy to patients with an increased risk of relapse. However in Medical Research Council (MRC) trial UKALL X two short myeloablative blocks of intensification therapy given at weeks 5 and 20 were of benefit to children in all risk groups. The successor trials, MRC UKALL XI and MRC ALL97, tested whether further intensification would continue to benefit all patients by randomising them to receive, or not, an extended third intensification block at week 35. After a median follow-up of 4 years (range 5 months to 8 years), 5 year projected event-free survival was superior at 68% for the 894 patients allocated a third intensification compared with 60% for the 887 patients who did not receive one (odds ratio 0.75, 95% CI 0.63-0.90, 2P = 0.002). This difference was almost entirely due to a reduced incidence of bone marrow relapses in the third intensification arm (140 of 891 in the third intensification arm vs. 171 of 883 in the no third intensification, 2P = 0.02). Subgroup analysis suggests benefit of the third intensification for all risk categories. Overall survival to date is no different in the two arms, indicating that a greater proportion of those not receiving a third intensification arm and subsequently relapsing can be salvaged. These results indicate that there is benefit of additional intensification for all risk subgroups of childhood ALL. [ABSTRACT FROM AUTHOR]

Against a background of ever increasing expenditure on blood safety, less attention has been paid to improving the safety of the transfusion chain within hospitals. Based on reports to the Serious Hazards of Transfusion (SHOT scheme) between 1996 and 2003, the risk of an error occurring during transfusion of a blood component is estimated at 1:16 500, an ABO incompatible transfusion at 1:100 000 and the risk of death as a result of an 'incorrect blood component transfused' (IBCT) is around 1:1 500 000. There are opportunities for error at a number of critical points in the transfusion chain, starting with the decision to transfuse, prescription and request, patient sampling, pretransfusion testing and finally the collection of the component from the blood refrigerator and administration to the patient, consistently the commonest error in successive SHOT reports. Successive 'Better Blood Transfusion' initiatives and the 2003 Annual Report of the Chief Medical Officer for England have drawn welcome attention to the importance of safe and appropriate transfusion and the National Patient Safety Agency has now set a target of reducing the number of ABO incompatible transfusions by 50% over 3-5 years.

The National Patient Safety Agency aims to generate an open and fair culture in the NHS where errors and near misses are reported, studied and learnt from. Safety rests in the design of equipment, systems, procedures, buildings and corporate frameworks, together with awareness of the human factors behind slips, lapses, mistakes and violations and how to anticipate and control them. Cultural shift can only be achieved if staff are willing to report and learn from such events and from near misses. It is a long way from the current widespread climate of blame and cover-up, but the change has begun.

This study was undertaken in order to compare the interphase and metaphase cytogenetics of 28 patients with ETV6/RUNX1 positive acute lymphoblastic leukemia, at diagnosis and relapse. The median time to relapse was 26 months. The significant fusion positive population heterogeneity revealed at interphase by a commercial probe for ETV6/RUNX1 fusion has not been described before. Six diagnostic samples had a single abnormal population; others had up to five each, which differed in the numbers of RUNX1 signals, and in the retention or loss of the second ETV6 signal. In contrast, the number of fusion signals was more constant. At relapse, there were fewer populations; the largest or unique clone was sometimes a re-emergence of a minor, diagnostic one, with a retained copy of ETV6 and the most RUNX1 signals. Abnormal, fusion negative clones were identified in bone marrow samples at extra-medullary relapse. Variant three or four-way translocations, which involved chromosomes 12 and 21, were prominent among the complex rearrangements revealed by metaphase FISH. The frequency of their occurrence at diagnosis and reappearance at relapse, sometimes accompanied by minor clonal evolution, was another new observation. Other recurrent cytogenetic features included a second copy of the fusion signal in six cases, partial duplication of the long arm of the X chromosome in two cases, and trisomy 10 in three cases. In comparing our data with previously reported cases, a picture is beginning to emerge of certain diagnostic features, which may provide circumstantial evidence of an increased risk of relapse., (Copyright 2005 Wiley-Liss, Inc.)

This study of children and adults with acute lymphoblastic leukaemia (ALL) is the largest series of patients with hypodiploidy (<46 chromosomes) yet reported. The incidence of 5% was independent of age. Patients were subdivided by the number of chromosomes; near-haploidy (23-29 chromosomes), low hypodiploidy (33-39 chromosomes) and high hypodiploidy (42-45 chromosomes). The near-haploid and low hypodiploid groups were characterized by their chromosomal gains and a doubled hyperdiploid population. Structural abnormalities were more frequent in the low hypodiploid group. Near-haploidy was restricted to children of median age 7 years (range 2-15) whereas low hypodiploidy occurred in an older group of median age 15 years (range 9-54). Patients with 42-45 chromosomes were characterized by complex karyotypes involving chromosomes 7, 9 and 12. The features shared by the few patients with 42-44 chromosomes and the large number with 45 justified their inclusion in the same group. Survival analysis showed a poor outcome for the near-haploid and low hypodiploid groups compared to those with 42-45 chromosomes. Thus cytogenetics, or at least a clear definition of the modal chromosome number, is essential at diagnosis in order to stratify patients with hypodiploidy into the appropriate risk group for treatment.

Objective: To measure the effect of seeing a photograph of the pelvic findings at laparoscopy., Setting: Two university teaching hospitals., Method: A randomised-controlled trial., Subjects: Two hundred thirty-three women undergoing diagnostic laparoscopy for the investigation of chronic pelvic pain., Interventions: At operation a Polaroid print was taken of the pelvis. If this was of satisfactory quality, the patient was randomly allocated to either see, or not see, the print during the postoperative consultation., Main Outcomes: Pain severity and pain belief scores at 3 and 6 months., Analysis: By intention to treat., Results: Postoperative consultations with photographs did not improve immediate understanding and satisfaction with the consultation. In addition, compared to controls, both patients and doctors did not perceive particular benefit for communication from the photograph. There was a consistent trend to more pain in the photographic reinforcement group and more negative pain beliefs. At 3 months, the average within person differences showed some benefit in visual analogue pain scores, McGill affect scores, 'permanence' and 'self-blame' scores. These benefits were not statistically significant. At 6 months, there was a consistent pattern of benefit from pain severity and pain beliefs, again these benefits were not statistically significant., Conclusion: No clear benefits result from showing patients photographs of their pelvis.

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.

The case records of 99 consecutive children with acute lymphoblastic leukaemia who received either 6-thioguanine (6-TG) or 6-mercaptopurine (6-MP) as maintenance therapy for at least 1 year were reviewed for hepatic veno-occlusive disease (VOD). Overall, 12% of those on 6-TG developed VOD (all boys). Isolated persistent thrombocytopenia appeared to be the earliest indicator of incipient VOD. Multivariate analysis identified male sex and 6-TG as risk factors. In all cases, VOD was mild and reversible on withdrawing 6-TG or replacing it with 6-MP. The data implicate a sex-linked polymorphic variation in xenobiotic pathways of thiopurine metabolism in the pathogenesis of VOD.

Children who have completed treatment for acute lymphoblastic leukaemia (ALL) are commonly followed up for the first 5 years with regular full blood counts (FBCs) to monitor for relapse of disease. There is little evidence to suggest that this practice improves the detection rate of unexpected relapse. Surveillance FBCs, performed on 43 children with relapsed ALL between 1990 and 1999, were analysed. Of the 42 relapses in children off therapy, only two were detected by an abnormal FBC. Routine FBCs in asymptomatic children off therapy lacks specificity in detecting unexpected relapses and maybe safely discontinued.

Purpose: The aim of this study was to compare leucocyte and erythrocyte thioguanine nucleotide (TGN) cytotoxic metabolite concentrations in children with lymphoblastic leukaemia taking mercaptopurine (MP) or thioguanine (TG) as part of their long-term remission maintenance chemotherapy., Methods: Ten consecutive children treated on the MRC ALL97 protocol were studied. Six were randomized to TG and four to MP. Leucocyte and erythrocyte thiopurine nucleotide metabolites were measured after the children had been titrated to the standard thiopurine protocol dose, or higher., Results: Children taking TG accumulated significantly higher erythrocyte TGN concentrations than those taking MP (median difference 1171 pmol/8 x 10(8) erythrocytes, 95% CI 766 to 2169, P<0.02), but there was no significant difference in the concentration range of leucocyte TGNs generated from TG or MP. In those children taking TG, median TGN concentrations were 5142 pmol/8 x 10(8) leucocytes and 1472 pmol/8 x 10(8) erythrocytes (3.5-fold difference, median difference 3390 pmol/8 x 10(8) cells, 95% CI 1559 to 7695, P=0.005), compared to 5422 pmol/8 x 10(8) leucocytes and 261 pmol/8 x 10(8) erythrocytes (20-fold difference, median difference 5054 pmol/8 x 10(8) cells, 95% CI 2281 to 6328, P=0.03) in those taking MP., Conclusions: Despite the accumulation of significantly higher erythrocyte TGN concentrations for TG compared with MP, the accumulation of leucocyte TGNs in children taking TG was similar to the range of leucocyte TGNs in children taking MP. Therefore, when correlating intracellular TGNs to clinical effect, the range of erythrocyte TGN metabolites will be higher for those children taking TG than in those taking MP.

Aims: Inherited differences in thiopurine methyltransferase (TPMT) activity are an important factor in the wide interindividual variations observed in the clinical response to thiopurine chemotherapy. The aim of this study was to establish a population range for red blood cell (RBC) TPMT activity in children with acute lymphoblastic leukaemia (ALL) at disease diagnosis. An additional aim was to investigate factors that can influence TPMT activity within the RBC., Methods: Blood samples were collected from children with ALL at disease diagnosis, prior to any blood transfusions, as part of the nationwide UK MRC ALL97 therapeutic trial. RBC TPMT activity was measured by h.p.l.c. RBCs were age-fractionated on Percoll density gradients., Results: Pretreatment blood samples were received from 570 children within 3 days of venepuncture. TPMT activities at disease diagnosis ranged from 1.6 to 23.6 units/ml RBCs (median 7.9) compared with 0.654-18.8 units (median 12.9), in 111 healthy control children (median difference 4.5 units, 95% CI 3.9, 5.1 units, P < 0.001). A TPMT quality control sample, aliquots of which were assayed in 60 analytical runs over a 12 month period, contained a median of 11.98 units with a CV of 11.6%. Seven children had their RBCs age-fractionated on density gradients. TPMT activities in the top gradient (young cells) ranged from 4.2 to 14.1 units (median 7.5) and in the bottom gradient (old cells) 1.5-12.6 units (median 4.7 units), median difference 2.3 units, 95% CI 0.7, 4.1, P = 0.035., Conclusions: Circulating RBCs do not constitute a homogeneous population. They have a life span of around 120 days and during that time undergo a progressive ageing process. The anaemia of ALL is due to deficient RBC production. The results of this study indicate that RBC TPMT activities are significantly lower in children with ALL at disease diagnosis. This may be due, at least in part, to a relative excess of older RBCs.

Childhood idiopathic thrombocytopenic purpura (ITP) is a largely trivial disorder from which over 95% of children sooner or later recover spontaneously, and for most of whom the risks of unnecessary or ineffective therapy are arguably greater than those of the untreated disease. There are, however, a few patients who continue to have very low platelet counts and remain symptomatic for many months or years. They are rare, and they present difficult management problems. Splenectomy is probably the most effective treatment but is also the most dangerous and is not always successful. It is also irreversible. Most other regimens are either ineffective, unacceptably toxic, or both. Planning management for an individual patient requires a realistic risk:benefit appraisal, a process that is impeded by inadequate epidemiological data and a scarcity of large-scale randomized clinical trials. International collaborative studies may help in the future.

Aims: To evaluate the pharmacokinetics of once daily (OD) gentamicin and its effectiveness as part of an OD regimen for the empirical treatment of febrile neutropenia in children with cancer., Subjects: 59 children aged 6 months to 16 years (mean (SD) 5.7 (4) years) with febrile neutropenia (neutrophil count < 0.5 x 10(9)/l) after chemotherapy., Methods: Over one year, 113 febrile neutropenic episodes were treated empirically with an OD antibiotic regimen of ceftriaxone (80 mg/kg; maximum 4 g) and gentamicin (7 mg/kg; infused over 60 minutes, no maximum). The patients were assessed after 48 hours., Results: 86 of the 113 episodes settled with the first line antibiotic regimen. In 29 episodes, blood cultures identified a causative bacterial pathogen; for 17 of these, the first line antibiotic regimen was adequate; in four episodes, although the episode settled, ceftriaxone was replaced by a more appropriate antibiotic and OD gentamicin was continued; in the remaining eight episodes, a glycopeptide antibiotic was deemed necessary. There was no failure of treatment in organisms sensitive to gentamicin, including Pseudomonas aeruginosa. In 27 episodes (24%), resolution was obtained by the empirical introduction of a second line regimen of ceftazidime and a glycopeptide antibiotic, and/or amphotericin. Gentamicin concentrations were measured in 110 episodes and they were all below the 24 hour line indicating that there was no need to change the dosing interval. In two episodes (2%), serum creatinine rose transiently by more than 50% of the baseline concentration. Although there was no vestibular toxicity, three of 30 children who underwent pure tone audiometry reported high frequency hearing loss in one ear., Conclusion: OD gentamicin can be used safely and effectively to treat febrile neutropenia in children with cancer. When used for a short period (< 5 days), in children not receiving other nephrotoxic drugs and who have normal serum creatinine, serum gentamicin estimations are unnecessary.

Speed of response to therapy predicts outcome in childhood lymphoblastic leukaemia. This observation has been made studying both blood and bone marrow in children on widely differing treatment regimens from the 1970s to the present day. It appears to be independent of other classical prognostic factors such as age and diagnostic white cell count. Currently some major collaborative groups are using the rate of initial disease clearance to risk-stratify subsequent therapy and this practice may increase. The best way to measure the rate of disease clearance remains to be defined. Watching disappearance of peripheral blood blasts is the least invasive method but possibly the least sensitive. Molecular quantitation of minimal residual disease (MRD) after achievement of conventional remission is much more sensitive but less specific. It cannot be applied to all patients and is costly and time consuming. The degree of marrow infiltration remaining after 7 or 14 days may fall between the two but is often difficult to estimate reliably and reproducibly due to technical limitations. The three techniques may reflect response to therapy in a way slightly different from each other and may not be direct correlates. The best compromise may be to use all three but to reserve MRD study only for those who clear their blood and bone marrow after 7 days.

Childhood lymphoblastic leukemia (ALL) is usually assumed to have been permanently eradicated in patients in long-term remission, but occasionally can recur after many years. To learn more about the problem, we studied a group of children whose leukemia had been in remission for 10 or more years before relapse and tried to determine whether they had true recurrences or second malignancies. We studied children treated on Medical Research Council ALL protocols between 1970 and 1984 and followed up by the Clinical Trial Service Unit in Oxford. Detailed clinical and laboratory data was collected from the centers concerned on all who were reported to have had a recurrence of their leukemia after 10 or more years from the time of achieving first complete remission (CR1). To prove that the relapse was a true recurrence rather than a second or secondary leukemia, DNA extracted from archived marrow smears was subjected to polymerase chain reaction (PCR) analysis for the presence of an identical Ig heavy chain (IgH) or T-cell receptor (TCR) gene rearrangement at initial diagnosis and subsequent relapse. A total of 1,134 of 2,746 children had survived 10 years or more (range, 10 to 24 years) in CR1 and of those, 12 (approximately 1%) had subsequently relapsed. Relapse blast cells were shown to express the common ALL antigen (CD 10) in all cases and an identical clonal IgH or TCR gene rearrangement was found on PCR analysis of DNA from diagnosis and relapse in all eight cases where DNA extraction was successful. A further program of therapy was successful in inducing a second CR in all patients, four of whom have succumbed to a second relapse after 12 to 27 months. The remaining eight are in continuing CR2 at a follow-up of 12 to 108 months (median, 52) from relapse. Although the risk of relapse of childhood ALL after 10 years in remission appears to be small (around 1%), it persists. This raises questions about how blasts can survive quiescent for so long and when we can truly be confident of cure, if ever.

As a prelude to a nationwide randomized trial of thioguanine (TG) versus mercaptopurine (MP) for childhood lymphoblastic leukaemia we compared a pilot group of 23 children taking TG with a matched group taking MP. We assessed drug tolerance based on haematological toxicity and measured erythrocyte (RBC) concentrations of thioguanine nucleotides (TGN). The median tolerated dose of TG was 30 mg/m2 compared to 55 mg/m2 for MP. There was no difference in the pattern of anaemia or neutropenia between the two groups, but dose-limiting thrombocytopenia was more evident in the TG children (P< 0.001), four of whom had a decrease in platelet count to <20 x 10(9)/l compared to only one on MP. The median RBC TGN concentration for those on 40 mg/m2 TG was 1726 pmol/8 x 10(8) RBCs compared with 308 pmol/8 x 10(8) RBCs for those on 75 mg/m2 MP (P< 0.0001). There was an inverse correlation between RBC TGNs and neutrophil count in the MP group but not in those on TG. No correlation between metabolite concentration and thrombocytopenia was found in either group. These results provide further evidence that TG has a selective effect on platelets. They also showed that RBC TGN were, on average, 5-fold higher in those taking TG but did not obviously relate to myelotoxicity as found in children on MP. The higher concentrations seen may partly reflect the erythrocyte's ability to metabolize TG directly to TGN by pathways not open to MP.

Platelet transfusions are undoubtedly effective in securing hemostasis in bleeding children with absent or nonfunctioning platelets. They are, however, abused in some circumstances and are not without risk. The use of platelet transfusions to prevent rather than to treat bleeding in children with malignant disease has increased several times over the last two decades. When joining in this widespread practice, physicians should be aware that there is a relatively unimpressive evidence base supporting it and also that for patients with uncomplicated myelo-suppression the most persuasive studies suggest that a threshold platelet count of 10 x 10(9)/L is no less effective than the more customary 20 x 10(9)/L is. Still lower thresholds await evaluation. For children with nonmalignant conditions the use of platelet transfusions should be carefully evaluated on a case-by-case basis, but they should normally be avoided in the absence of clinically important bleeding. Neonates with thrombocytopenia, particularly those with immune disease due to a maternal alloantibody, are considered an exception to this generalization. The serious hazards of platelet transfusions include alloimmunization and the induction of refractoriness, graft-versus-host (GVH) disease, and the transmission of infection, all of which can be life threatening. Less risky alternative therapeutic approaches may become more widely available in the future, including recombinant thrombopoietin and lyophilized heat-treated platelet membrane preparations.

Aims: The response to 6-mercaptopurine (6MP) is highly variable. Its antileukaemic effect can be related to drug derived 6-thioguanine nucleotides (TGNs). The inherited level of thiopurine methyltransferase (TPMT) activity may be a major factor in the clinical response to 6MP because TPMT forms methylmercaptopurine metabolites (MeMPs) at the expense of TGNs. The aim of this study was to explore the clinical importance of TPMT phenotype., Methods: Thiopurine metabolism was studied in a consecutive cohort of children with acute lymphoblastic leukaemia (ALL) treated according to the Medical Research Council trial UK ALL XI. TPMT phenotype was measured in 38 children at diagnosis, and thiopurine metabolites were measured at defined times during 2 years treatment in 29 of these children., Results: TPMT activities at diagnosis ranged from 5.5 to 18.5 units ml(-1) packed RBCs, no different from the range of activities reported in healthy children. TGNs and MeMPs measured during the first 6MP cycle at 75 mg m(-2) ranged from 187 to 594 pmol 6TGNs, median 327, and 0.5 to 22.0 nmol MeMPs, median 4.5, per 8 x 10(8) RBCs. TPMT activity was not significantly related to the generation of MeMPs (r(s) = 0.06), but was negatively correlated to 6TGNs (r(s) = -0.44, P<0.025, n=29). TGNs were related to neutropenia at the point of dose reduction (r(s) = -0.5, P<0.01). TPMT activity was also inversely related to the duration of cytopenia driven 6MP withdrawal (r(s)= -0.41, P<0.05)., Conclusions: These findings support the suggestion that the inherited activity of TPMT in a given individual can modulate the cytotoxic effect of 6MP, and this information may help in clinical management.