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Myelotoxicity during thiopurine therapy is enhanced in patients, who because of single nucleotide polymorphisms have decreased activity of the enzyme thiopurine methyltransferase (TPMT) and thus more thiopurine converted into 6-thioguanine nucleotides. Of 601 children with acute lymphoblastic leukemia (ALL) who were treated by the NOPHO ALL-92 protocol, 117 had TPMT genotype determined, whereas for 484 patients only erythrocyte TPMT activity was available. The latter were classified as heterozygous, if TPMT activity was <14 IU/ml, or deficient (<1.0 IU/ml). 526 patients had TPMT wild type, 73 were presumed heterozygous, and two were TPMT deficient. Risk of relapse was higher for the 526 TPMT wild type patients than for the remaining 75 patients (18 vs 7%, P =0.03). In cox multivariate regression analysis, sex (male worse; P =0.06), age (higher age worse, P =0.02), and TPMT activity (wild type worse; P =0.02) were related to risk of relapse. Despite a lower probability of relapse, patients in the low TPMT activity group did not have superior survival ( P =0.82), possibly because of an excess of secondary cancers among these 75 patients ( P =0.07). These data suggest that children with ALL and TPMT wild type might have their cure rate improved, if the pharmacokinetics/-dynamics of TPMT low-activity patients could be mimicked without a concurrent excessive risk of second cancers.

Background: As the number of cancer survivors increases, their health and welfare have come into focus. Thus, long-term medical consequences of cancer at a young age (<25 years), obtained from social security benefit records, were studied. Methods: Standardised incidence ratios (SIRs) of long-term medical consequences for 5-year cancer survivors, born during 1965–1985, were explored by linking population-based registries in Norway. Results: Among the 5-year cancer survivors (4031 individuals), 29.7% received social security benefits. The survivors had an overall 4.4 times (95% confidence interval (95% CI): 4.1–4.6) higher risk of social security benefit uptake than the cancer-free population. Survivors of malignancies of bone and connective tissues (SIR: 10.8; 95% CI: 9.1–12.9), CNS tumours (SIR: 7.7; 95% CI: 6.9–8.6) and malignancies of the haematopoietic system (SIR: 6.1; 95% CI: 5.3–7.0) had the highest risks of social security benefits uptake. The most notified causes of social security benefit uptake were diseases of the nervous system, and injury and poisoning. Conclusion: The uptake of social security benefits among 5-year cancer survivors increased substantially and it may represent a solid outcome measure for the burden of the most severe late effects, especially in countries with comparable social welfare systems.

Drug doses, blood levels of drug metabolites and myelotoxicity during 6-mercaptopurine/methotrexate (MTX) maintenance therapy were registered for 59 adolescents (⩾10 years) and 176 non-adolescents (<10 years) with B-cell precursor acute lymphoblastic leukemia (ALL) and a white blood cell count (WBC) <50 × 10 9 /l at diagnosis. Event-free survival was lower for adolescents than non-adolescents (pEFS 12y :0.71 vs 0.83, P =0.04). For adolescents staying in remission, the mean WBC during maintenance therapy (mWBC) was related to age ( r S =0.36, P =0.02), which became nonsignificant for those who relapsed ( r S =0.05, P =0.9). The best-fit multivariate Cox regression model to predict risk of relapse included mWBC and thiopurine methyltransferase activity, which methylates mercaptopurine and reduces the intracellular availability of cytotoxic 6-thioguanine nucleotides (coefficient: 0.11, P =0.02). The correlation of mWBC to the risk of relapse was more pronounced for adolescents (coefficient=0.65, P =0.003) than for non-adolescents (coefficient=0.42, P =0.04). Adolescents had higher mean neutrophil counts ( P =0.002) than non-adolescents, but received nonsignificantly lower mercaptopurine and MTX doses during maintenance therapy. Red blood cell MTX levels were significantly related to the dose of MTX among adolescents who stayed in remission ( r S =0.38, P =0.02), which was not the case for those who developed a relapse ( r S =0.15, P =0.60). Thus, compliance to maintenance therapy may influence the risk of relapse for adolescents with ALL.

Survivors of childhood cancer are at increased risk for a wide range of late effects. However, no large population-based studies have included the whole range of somatic diagnoses including subgroup diagnoses and all main types of childhood cancers. Therefore, we aimed to provide the most detailed overview of the long-term risk of hospitalisation in survivors of childhood cancer. From the national cancer registers of Denmark, Finland, Iceland, and Sweden, we identified 21,297 5-year survivors of childhood cancer diagnosed with cancer before the age of 20 years in the periods 1943-2008 in Denmark, 1971-2008 in Finland, 1955-2008 in Iceland, and 1958-2008 in Sweden. We randomly selected 152,231 population comparison individuals matched by age, sex, year, and country (or municipality in Sweden) from the national population registers. Using a cohort design, study participants were followed in the national hospital registers in Denmark, 1977-2010; Finland, 1975-2012; Iceland, 1999-2008; and Sweden, 1968-2009. Disease-specific hospitalisation rates in survivors and comparison individuals were used to calculate survivors' standardised hospitalisation rate ratios (RRs), absolute excess risks (AERs), and standardised bed day ratios (SBDRs) based on length of stay in hospital. We adjusted for sex, age, and year by indirect standardisation. During 336,554 person-years of follow-up (mean: 16 years; range: 0-42 years), childhood cancer survivors experienced 21,325 first hospitalisations for diseases in one or more of 120 disease categories (cancer recurrence not included), when 10,999 were expected, yielding an overall RR of 1.94 (95% confidence interval [95% CI] 1.91-1.97). The AER was 3,068 (2,980-3,156) per 100,000 person-years, meaning that for each additional year of follow-up, an average of 3 of 100 survivors were hospitalised for a new excess disease beyond the background rates. Approximately 50% of the excess hospitalisations were for diseases of the nervous system (19.1% of all excess hospitalisations), endocrine system (11.1%), digestive organs (10.5%), and respiratory system (10.0%). Survivors of all types of childhood cancer were at increased, persistent risk for subsequent hospitalisation, the highest risks being those of survivors of neuroblastoma (RR: 2.6 [2.4-2.8]; n = 876), hepatic tumours (RR: 2.5 [2.0-3.1]; n = 92), central nervous system tumours (RR: 2.4 [2.3-2.5]; n = 6,175), and Hodgkin lymphoma (RR: 2.4 [2.3-2.5]; n = 2,027). Survivors spent on average five times as many days in hospital as comparison individuals (SBDR: 4.96 [4.94-4.98]; n = 422,218). The analyses of bed days in hospital included new primary cancers and recurrences. Of the total 422,218 days survivors spent in hospital, 47% (197,596 bed days) were for new primary cancers and recurrences. Our study is likely to underestimate the absolute overall disease burden experienced by survivors, as less severe late effects are missed if they are treated sufficiently in the outpatient setting or in the primary health care system. Childhood cancer survivors were at increased long-term risk for diseases requiring inpatient treatment even decades after their initial cancer. Health care providers who do not work in the area of late effects, especially those in primary health care, should be aware of this highly challenged group of patients in order to avoid or postpone hospitalisations by prevention, early detection, and appropriate treatments.

Inactivation of the Ink4 gene locus locus on 9p comprising the tumour suppressor gene p16ink4a and its neighbours p14ARF and p15ink4b is common in childhood acute lymphoblastic leukaemia (ALL), but the prognostic significance is controversial. DNA from 230 patients was retrospectively analysed by Southern blotting, single strand conformation polymorphism (SSCP) and sequencing techniques. The results were correlated with clinical characteristics and outcome. One hundred and ninety-four fully analysed patients, similarly treated using the Nordic NOPHO-86 or the current NOPHO-92 protocols, were included in the outcome analysis. Deletions approached a minimally deleted region between the p16ink4a and p15ink4b genes, making the p14ARF gene the most commonly deleted coding sequence. Bi-allelic deletion was associated with high white blood cell count (WBC) (P < 0.001), T cell phenotype (P < 0.001) and mediastinal mass (P < 0.001). Patients with Ink4 locus bi-allelic deletions had an inferior pEFS (P < 0.01) and multivariate analysis indicated that bi-allelic deletion of the p16ink4a and the p14ARF genes was an independent prognostic risk factor (P < 0.05). Sub-group analysis revealed a pronounced impact of deletion status for high-risk patients, ie with high WBC. Deletion-status and clinical risk criteria (WBC) could thus be combined to further differentiate risk within the high-risk group. The analysis of the Ink4 locus adds independent prognostic information in childhood ALL treated by Nordic protocols and may help in selection of patients for alternative treatment.

Children with high-risk neuroblastoma (NB) have a poor clinical outcome. The purpose of the present study was to evaluate different strategies for immunotherapy of high-risk NB based on vaccination with antigen-loaded dendritic cells (DCs). DCs are professional antigen-presenting cells with the ability to induce antitumor T-cell responses. We have compared DCs either loaded with apoptotic tumor cells or transfected with mRNA from the NB cell line HTB11 SK-N-SH, for their capacity to induce T-cell responses in vitro . Monocyte-derived DCs from healthy donors were loaded with tumor-derived antigens in the form of apoptotic cells or mRNA, matured and used to prime autologous T cells in vitro . After 1 week, T-cell responses against antigen-loaded DCs were measured by ELISPOT assay. DCs loaded with apoptotic NB cells or transfected with NB-cell mRNA were both able to efficiently activate autologous T cells. Both T cells of the CD8+ and CD4+ subset were activated. T cells activated by NB mRNA transfected DCs extensively crossreacted with DCs loaded with apoptotic NB cells and vice versa . The results indicate that loading of DCs with apoptotic NB cells or transfection with tumor mRNA represent promising strategies for development of individualized cancer vaccines/cancer gene therapy in treatment of NB.

Objective: Cardiac catheterization is an important and frequent diagnostic intervention in children, but few systematic studies have explored the associated venous thrombotic complications. We have prospectively evaluated the prevalence of venous thrombosis, diagnosed by ultrasonography, in children catheterized at our department. Materials and methods: We examined 50 children with weight greater than seven kilograms for thrombosis of the femoral vessels. Prophylactic anticoagulation was given to half of the children who were to undergo left-sided catheterization. The enrolled children had ultrasonography of the site of puncture the day before, and the day after, the cardiac catheterization. During catheterization, blood samples were taken from 33 of the children for analysis of thrombophilic agents. Results: The children, with a median age of 34 months, had been catheterized 103 times, comprising the 50 current and 53 previous procedures. Over the course of the current procedure, interventions of various types were performed in 18 children (36%). We diagnosed thrombophilic predispositions in four patients. Despite the thrombophilic tendencies, and a high frequency of interventions, we did not encounter a single case of femoral venous thrombosis. Nor did we find any evidence of arterial thrombosis. Conclusion: Our study indicates that catheterization procedures in children are currently associated with a low prevalence of femoral venous thrombosis. Continuous assessment of vascular complications, nonetheless, is still required to prevent late effects, and to ensure the best quality of cardiac catheterisations in children.

To the Editor: Treatment of cancers in childhood often involves a short intravenous infusion of high-dose methotrexate (>30 mg per kilogram of body weight) followed by \"rescue\" therapy with leucovorin (5-formyl-tetrahydrofolate). Concurrent intraspinal infusion of methotrexate may also be used. 1 This treatment may be performed during general anesthesia. Nitrous oxide anesthesia is often used in pediatric oncology units. There is, however, evidence that the drug combination of nitrous oxide and methotrexate may be hazardous. Methotrexate acts by inhibiting the enzyme dihydrofolate reductase and thereby blocks the regeneration of tetrahydrofolate from dihydrofolate. 2 This results in the inhibition of several processes dependent . . . No extract is available for articles shorter than 400 words.