Quality Control for Microarray Experiments

Objectives: In this paper we give an overview of post-hybridization quality control methods for gene expression chips, including methods for the gene/spot level, the hybridization/chip level and the process level. We present quality control methods that can be applied after hybridization and image analysis, i.e. that use data from the chip experiment itself. Wet lab quality control steps, which should be applied before the probe is measured on a chip, are not discussed. This review is aimed towards statisticians and data analysts.

Methods: We give examples of some of the quality control measures available for spotted cDNA and Affymetrix GeneChips®, the most common chip types. As quality control measures are technology and design-dependent, we will stress on methods that have the potential to be applied platform-independently.

Results: Quality control should identify poor quality chips or hybridizations, as well as faulty measurements for individual genes/spots. Additionally, high throughput laboratories processing several tens or hundreds of microarrays per week have the need for an appropriate process control to be able to identify changes in the production process as early as possible.

Conclusion: Microarrays have become a standard research tool for biologists and medical researchers. As a consequence, there is a great need for standardized quality control, as false findings due to problem in data quality can lead to a substantial loss of resources.

Busulfan-melphalan in high-risk neuroblastoma: the 30-year experience of a single institution

High-dose chemotherapy (HDC) was investigated in high-risk neuroblastoma (HR-NBL) to reduce the risk of relapse. We report the results of the 30-year experience of a cohort of patients with HR-NBL treated with high-dose (HD) busulfan (Bu)-containing regimens. From 1980 to 2009, 215 patients aged >1 year with stage 4 NBL were treated with HD Bu-containing regimens at Gustave Roussy. These data were prospectively recorded in the Pediatric Transplantation Database. The median age at diagnosis was 40 months (12-218 months). All patients had a stage 4 neuroblastoma. NMYC amplification was displayed in 24% of the tumors. The hematopoietic support consisted of bone marrow or PBSCs in 46% and 49% of patients, respectively. The 5-year event-free survival and overall survival rates of the whole cohort were 35.1% and 40%, respectively. Age at diagnosis, bone marrow involvement and tumor response after induction chemotherapy were significant prognostic factors. Toxicity was manageable and decreased over time, owing to both PBSC administration and better supportive care. Based on this experience, HD Bu-melphalan (Mel) has been implemented in Europe and compared with Carboplatin-Etoposide-Mel in the European SIOP Neuroblastoma (SIOPEN)/HR-NBL randomized protocol. It has now become the standard HDC in the SIOPEN HR strategy.

Magnetism of the chromium thio-spinels Fe1-xCuxCr2S4 studied using muon spin rotation and relaxation

Powder samples of Fe1-xCuxCr2S4 with x = 0,0.2,0.5,0.8 were studied, between 5 and 300 K. The results reveal that for x < 1, the magnetic order in the series is more varied than the simple collinear ferrimagnetic structure traditionally assumed to exist everywhere from the Curie point to T → 0. In FeCr2S4 several ordered magnetic phases are present, with the ground state likely to have an incommensurate cone-like helical structure. Fe0.8Cu0.2Cr2S4 is the compound for which simple collinear ferrimagnetism is best developed. In Fe0.5Cu0.5Cr2S4 the ferrimagnetic spin structure is not stable, causing spin reorientation around 90 K. In Fe0.2Cu0.8Cr2S4 the ferrimagnetic structure is at low temperatures considerably distorted locally, but with rising temperature this disorder shows a rapid reduction, coupled to increased spin fluctuation rates. In summary, the present data show that the changes induced by the replacement of Fe by Cu have more profound influences on the magnetic properties of the Fe1-xCuxCr2S4 compounds than merely a shift of Curie temperature, saturation magnetization and internal field magnitude.

Procalcitonin guidance and reduction of antibiotic use in acute respiratory tract infection

Increasing worldwide development of antimicrobial resistance and the association of resistance development and antibiotic overuse make it necessary to seek strategies for safely reducing antibiotic use and selection pressure. In a first step, in a non-interventional study, the antibiotic prescription rates, initial procalcitonin (PCT) levels and outcome of 702 patients presenting with acute respiratory infection at 45 primary care physicians were observed. The second part was a randomised controlled non-inferiority trial comparing standard care with PCT-guided antimicrobial treatment in 550 patients in the same setting. Antibiotics were recommended at a PCT threshold of 0.25 ng·mL(-1). Clinical overruling was permitted. The primary end-point for non-inferiority was number of days with significant health impairment after 14 days. Antibiotics were prescribed in 30.3% of enrolled patients in the non-interventional study. In the interventional study, 36.7% of patients in the control group received antibiotics as compared to 21.5% in the PCT-guided group (41.6% reduction). In the modified intention-to-treat analysis, the numbers of days with significant health impairment were similar (mean 9.04 versus 9.00 for PCT-guided and control group, respectively; difference 0.04; 95% confidence interval -0.73-0.81). This was also true after adjusting for the most important confounders. In the PCT group, advice was overruled in 36 cases. There was no significant difference in primary end-point when comparing the PCT group treated as advised, the overruled PCT group and the control group (9.008 versus 9.250 versus 9.000 days; p = 0.9605). A simple one-point PCT measurement for guiding decisions on antibiotic treatment is non-inferior to standard treatment in terms of safety, and effectively reduced the antibiotic treatment rate by 41.6%.

Low temperature incommensurately modulated and noncollinear spin structure in FeCr2S4

FeCr(2)S(4) orders magnetically at T(N)≈ 170 K. According to neutron diffraction, the ordered state down to 4.2 K is a simple collinear ferrimagnet maintaining the cubic spinel structure. Later studies, however, claimed trigonal distortions below ∼ 60 K coupled to the formation of a spin glass type ground state. To obtain further insight, muon spin rotation/relaxation (μSR) spectroscopy was carried out between 5 and 200 K together with new (57)Fe Mössbauer measurements. Below ∼ 50 K, our data point to the formation of an incommensurately modulated noncollinear spin arrangement like a helical spin structure. Above 50 K, the spectra are compatible with collinear ferrimagnetism, albeit with a substantial spin disorder on the scale of a few lattice constants. These spin lattice distortions become very large at 150 K and the magnetic state is now better characterized as consisting of rapidly fluctuating short-range ordered spins. The Néel transition is of second order, but ill defined, extending over a range of ∼ 10 K. The Mössbauer data around 10 K confirm the onset of orbital freezing and are also compatible with the noncollinear order of iron. The absence of a major change in the quadrupole interaction around 50 K renders the distortion of crystal symmetry to be small.

Ovarian function after high-dose chemotherapy in childhood: Risk factors for developing partial ovarian failure and how to identify them early

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Background: During the last 30 years, polychemotherapies, surgery and radiotherapy have been established as standard therapies for treating pediatric cancers thus leading to a significant improvement in terms of 5-year-overall-survival which is now around 70% among children and adolescents. On the other hand, these treatments cause severe sequelae such as ovarian failure (OF) in young girls leading to a premature menopause and infertility. Methods: 29 patients treated at the Institute Gustave Roussy (Villejuif, France) have been investigated in an attempt to find biological and/or clinical markers, and imaging predictive of a partial ovarian insufficiency leading to an early menopause. Eligibility criteria: age >12 years at time of analysis; peripheral stem cell graft between 2–20 years; high dose chemotherapy. Results: 23/29 were eligible for this analysis (6 withdrawn due to oral contraception). 13/23 patients (56.5%) show no clinical evidence of ovarian treatment-related toxicity with a 13 years median time to transplant. 10/23 (43.5%) have complete ovarian insufficiency, among whom the majority have already received substitution hormone therapy (SHT). Out of 75% of pre-pubescent patients at transplant, only 2 have OF. All patients grafted at puberty (15.3 years) have high-dose chemotherapy-related immediate or definitive OF. Thiotepa >900mg/mq is castrating (odds ratio-10.1; p-0.04). Dosages of anti-müllerian hormone (AMH) collapses in patients with IO (p=0.002). Mensed patients have lower AMH dosages compared to normal population (p=2.10-e9) as for antral follicule count (>2mm). Conclusions: 1) 13/23 patients show no evidence of OF. 2) Main risk factors of OF: age ≥ 12 years; post pubertal status; thiotepa >900 mg/m2 (OR=10.1 and p=0.04). 3) Despite normal menses, many women who underwent high dose chemotherapy exhibit low AMH and Inhibine B levels and low count of follicles at a young age. These are possible markers of ovarian depletion. Cryopreservation of the ovarian cortex should be proposed to patients grafted due to a cancer independently of the age at which they have undergone high-dose chemotherapy.

No significant financial relationships to disclose.

A writing workshop for children with cancer

We present and comment on several short texts written in a writing workshop by children and adolescents treated for cancer. In addition to the obvious themes, the patients communicate the intense elements of the experience they are going through, including fear of injections, fear of not being cured, revolt, hope and a feeling of unreality, and raise the question "Why?". They are proud to express their feelings, thoughts and creativity, and relieved to be able show that they remain themselves. This can help them maintain or regain confidence in themselves and in the ability of their parents and medical staff to understand them. We consider their pleasure, their parents' and caregivers' reactions and the quality of their work as it relates to their age, academic level, cultural environment and cognitive capacities. These examples may help to inform physicians and nurses about how they perceive patients (children or adults) and their needs and abilities, and thereby improve the quality of the relationship.

Risk factors for hepatic veno-occlusive disease: a retrospective unicentric study in 116 children autografted after a high-dose BU-thiotepa regimen

At our Institute, during the last decade, the incidence of hepatic veno-occlusive disease (HVOD) appears to be on the increase among pediatric patients treated with BU-thiotepa (BU-TTP)-conditioning regimen. We thus performed a retrospective analysis to identify the risk factors for HVOD, which could explain such a change. In total, 116 patients treated at Institut Gustave Roussy, between May 1998 and December 2005 were eligible for this study having received BU-TTP as their first high-dose chemotherapy regimen, followed by autologous hematopoietic SCT (AHSCT). According to McDonald's clinical criteria, HVOD was diagnosed in 31% of these children. Demographic, clinical, biological and therapeutic parameters were evaluated in uni- and multivariate analyses that showed a significant correlation between previous carboplatin therapy and risk of developing post transplant HVOD (P=0.028). Comparable results were found for etoposide (P=0.048). In addition, a correlation between HVOD and risk of post transplant death was linked to its association with other types of organ failure (P=0.029). This study demonstrates that previous VPCARBO administration in conventional chemotherapy significantly increases the risk of HVOD among brain tumor patients later consolidated with BU-TTP followed by AHSCT.

Elevated plasma ferritin and busulfan pharmacodynamics during high-dose chemotherapy regimens in children with malignant solid tumors

Hepatic veno-occlusive disease (HVOD) is a frequent complication during hematopoietic stem-cell transplantation (HSCT). A strong relationship has been demonstrated between busulfan exposure and HVOD for busulfan-cyclophosphamide and allogeneic HSCT in adults. Busulfan disposition after the first intake was studied in 77 children treated for solid malignancies with high-dose busulfan-containing regimens and autologous HSCT. Busulfan was combined with cyclophosphamide and melphalan (n=30), melphalan (n=27), and thiotepa (n=20). No relationship was observed between busulfan exposure and HVOD. In contrast, plasma ferritin at baseline was higher in patients with HVOD (750 ng/ml (20-3,110)) compared with those without HVOD (189 ng/ml (8-3,967), P=0.012). Multivariate analysis showed that a ferritin level exceeding 300 ng/ml was the only risk factor for HVOD with an odds ratio of 4.0 (confidence interval 95% (1.5-11.2), P=0.0071). A high ferritin level at baseline was explained by the diagnosis of neuroblastoma, related treatments and transfusions.

Haematopoietic stem cell transplantation trends in children over the last three decades: a survey by the paediatric diseases working party of the European Group for Blood and Marrow Transplantation

This paper describes the trends in haematopoietic stem cell transplantation (HSCT) activity for children in Europe over the last three decades. We analysed 31,713 consecutive paediatric HSCTs reported by the European Group for Blood and Marrow Transplantation (EBMT) centres between 1970 and 2002. Data were taken from the EBMT registry and were compared according to period and centre category (paediatric or combined). Since 1996, there has been a significant increase in the number of HSCTs performed exclusively by paediatric centres, as well as in the number of alternative donor HSCTs, and in the use of peripheral blood stem cells (P<0.0001). The number of allogeneic HSCTs (allo-HSCTs) for acute lymphoblastic leukaemia, acute myeloblastic leukaemia and chronic myeloid leukaemia remained stable, whereas it increased for myelodysplastic syndromes and lymphomas, and decreased significantly for non-malignant diseases (P<0.0001). Multivariate analysis showed that younger age, human leukocyte antigen genoidentical donors, HSCT performed after 1996 and transplant centres performing more than 10 allo-HSCT/year were all associated with decreased transplant-related mortality (TRM) (P<0.0001). The number of autologus HSCTs (auto-HSCTs) for acute leukaemia decreased significantly, whereas it increased for solid tumours (P<0.0001). Multivariate analysis showed that both auto-HSCT performed before 1996 and paediatric solid tumours (P<0.0001) had higher TRM. Indications for paediatric HSCT have changed considerably during the last seven years. These changes provide tools for decision making in health-care planning and counselling.

[Malignant solid tumors in neonates: a study of 71 cases]

Malignant neonatal tumors are rare and comprise 2% of childhood malignancies. Clinical features, histologic types, prognosis were very different from those seen in older children, facing oncologists with diagnostic, therapeutic and ethical problems.

PATIENTS AND METHODS

In a retrospective study from January 1987 to January 2004, we reviewed the management of neonates treated at the Institute Gustave Roussy for a malignant solid tumor for whom symptoms started in the first month of life.

RESULTS

Seventy-one neonates were treated, comprising 1,2% of the overall patients treated during the same period of time. Of these 71 patients, 42 (59%) presented with neuroblastomas, 12 (17%) with mesenchymal tumors, 6(8%) with cerebral tumors and 11 with various other types of tumors. Fifty-nine patients underwent surgical resection. Thirty-eight neonates received chemotherapy, administered at a 30 to 50% reduced dose. Hematologic toxicities and infections were the main therapeutic complications. Very small doses of radiotherapy were used in only 5 children. There has been no therapy-related mortality. Twenty-two of the 57 survivors have sequelae, especially patients with intraspinal neuroblastoma. The 5 year overall survival was 79%.

CONCLUSIONS

Neonatal malignant solid tumors, except for cerebral tumors, have a good prognosis. The young age of patients resulted in problems of treatment tolerance. The therapeutic regimen should take into account the risk of acute iatrogenic toxicity and long term sequelae. Surgery remains the treatment of choice but chemotherapy, with dose reduction, managed by expert teams, is essential and safer in a lot of case.

siRNA-mediated AML1/MTG8 depletion affects differentiation and proliferation-associated gene expression in t(8;21)-positive cell lines and primary AML blasts

The chromosomal translocation t(8;21) is associated with 10-15% of all cases of acute myeloid leukaemia (AML). The resultant fusion protein AML1/MTG8 interferes with haematopoietic gene expression and is an important regulator of leukaemogenesis. We studied the effects of small interfering RNA (siRNA)-mediated AML1/MTG8 depletion on global gene expression in t(8;21)-positive leukaemic cell lines and in primary AML blasts using cDNA arrays, oligonucleotide arrays and real-time reverse transcription-polymerase chain reaction (RT-PCR). Suppression of AML1/MTG8 results in the increased expression of genes associated with myeloid differentiation, such as AZU1, BPI, CTSG, LYZ and RNASE2 as well as of antiproliferative genes such as IGFBP7, MS4A3 and SLA both in blasts and in cell lines. Furthermore, expression levels of several genes affiliated with drug resistance or indicative of poor prognosis AML (BAALC, CD34, PRG2, TSPAN7) are affected by AML1/MTG8 depletion. In conclusion, siRNA-mediated suppression of AML1/MTG8 cause very similar changes in gene expression pattern in t(8;21)-positive cell lines and in primary AML blasts. Furthermore, the results suggest that the specific targeting of AML1/MTG8 function may be a promising approach for complementing existing treatment strategies.

Expression profiling of Wilms tumors reveals new candidate genes for different clinical parameters

Wilms tumor is the most frequent renal neoplasm in children, but our understanding of its genetic basis is still limited. We performed cDNA microarray experiments using 63 primary Wilms tumors with the aim of detecting new candidate genes associated with malignancy grade and tumor progression. All tumors had received preoperative chemotherapy as mandated by the SIOP protocol, which sets this study apart from related approaches in the Unites States that are based on untreated samples. The stratification of expression data according to clinical criteria allowed a rather clear distinction between different subsets of Wilms tumors. Clear-cut differences in expression patterns were discovered between relapse-free as opposed to relapsed tumors and tumors with intermediate risk as opposed to high risk histology. Several differentially expressed genes, e.g.TRIM22, CENPF, MYCN, CTGF, RARRES3 and EZH2, were associated with Wilms tumor progression. For a subset of differentially expressed genes, microarray data were confirmed by real-time RT-PCR on the original set of tumors. Interestingly, we found the retinoic acid pathway to be deregulated at different levels in advanced tumors suggesting that treatment of these tumors with retinoic acid may represent a promising novel therapeutic approach.

High-dose busulfan and thiotepa followed by autologous stem cell transplantation (ASCT) in previously irradiated medulloblastoma patients: high toxicity and lack of efficacy

We previously demonstrated that Busulfan-Thiotepa (Bu-Thio) and ASCT effectively treated patients with locally relapsed medulloblastoma after surgery and conventional chemotherapy. We thus evaluated the administration of Bu-Thio in patients relapsing after conventional CNS irradiation. Patients were scheduled to receive Busulfan (600 mg/m(2)) and Thiotepa (900 mg/m(2)) and ASCT. Resection of residual tumour and additional irradiation were performed if necessary and feasible after Bu-Thio. Toxicity was compared to that observed in 35 patients treated without previous CNS irradiation. From 5/88 to 3/02, 15 patients were treated according to this strategy. Toxicity was significantly higher than that observed in unirradiated patients: thrombocytopenia <50,000/mm(3) lasting 56 days (13-732) (P=0.02) and 30 days (4-124), respectively, HVOD (10/15 and 12/35 patients, respectively) (P=0.06), neurological toxicity (8/15 vs 3/35 patients) (P=0.01). Tumour response was assessable in seven patients and consisted in two CR, three PR and two NR. Currently, two of 15 patients are alive with no evidence of disease. In conclusion, the toxicity of Bu-Thio was significantly more severe in previously irradiated patients. In spite of a high response rate, this strategy failed to improve the prognosis of previously irradiated patients with a relapse from a medulloblastoma.

Encéphalopathie induite par l'ifosfamide : 15 observations

INTRODUCTION

Ifosfamide is an alkylating agent used in the treatment of germ-cell tumors, sarcomas and lymphomas. One of its main side effects is the encephalopathy of which the incidence may reach 30% in the literature, in adults and children just as well.

OBJECTIVES

Based on both our experience and a review of the literature, we propose some recommendations for the management of this complication.

PATIENTS AND METHODS

We report 15 encephalopathy cases in non-brain tumor patients, which occurred between January 1987 and March 2002 in children from 2 to 17 years old, treated for solid tumors at the Institut Gustave Roussy. Ifosfamide was administered at a posology between 5.4 and 15 g/m(2)/course, associated with other antimitotics such as actinomycin D, etoposide or vincristine.

RESULTS

Six patients experienced a grade III neurological toxicity according to the NCI classification, which developed as excess drowsiness lasting up to 36 hours. Six other patients developed grade IV neurotoxicity, including two comas resolving within 4 days and four short generalized convulsions. Three other children experienced grade II drowsiness. Brain MRIs were normal and EEG showed an aspecific encephalopathy tracing. This early central neurotoxicity appeared right from the first administration, and occurred immediately after the first injection or during the second or third day of treatment. It was most often reversible, usually 3 to 5 days after the last ifosfamide administration. Five patients were administered a treatment with Methylene Blue with a demonstrable efficacy in only one case. No death or neurological sequelae have been noted. Ifosfamide has been renewed after the neurological accident in 7 of those patients. Only 1 of those 7 patients developed grade IV neurotoxicity during the next course of treatment. In 2 of those 7 children, Methylene Blue was used in a prophylactic way. No neurological disorders have been noted during the next courses of treatment.

DISCUSSION

In the literature, the following are described as risk factors for ifosfamide encephalopathy: advanced pelvic disease, previous cisplatyl treatment and renal failure. We have not found any of these predisposing factors in our series, but three of the fifteen patients had severe neurotoxicity associated with Vincristin during previous treatments.

CONCLUSION

Facing a clinical diagnosis of ifosfamide encephalopathy, it is recommended to discontinue administration of ifosfamide and inject by intravenous route 50 mg Methylene Blue every 4 hours until the symptomatology recedes. The re-challenge of Ifosfamide is not contra-indicated and should be performed under prophylactic treatment with Methylene Blue by intravenous route at the dose of 50 mg every 6 hours.

Inhibition of retinoic acid receptor signaling by Ski in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease with multiple different cytogenetic and molecular aberrations contributing to leukemic transformation. We compared gene expression profiles of 4608 genes using cDNA-arrays from 20 AML patients (nine with -7/del7q and 11 with normal karyotype) with 23 CD34+ preparations from healthy bone marrow donors. SKI, a nuclear oncogene, was highly up regulated. In a second set of 183 AML patients analyzed with real-time PCR, the highest expression level of SKI in AML with -7/del7q could be confirmed. As previously described, Ski associates with the retinoic acid receptor (RAR) complex and can repress transcription. We wanted to investigate the interference of Ski with RARalpha signaling in AML. Ski was co-immunoprecipitated and colocalized with RARalpha. We also found that overexpression of wild-type Ski inhibited the prodifferentiating effects of retinoic acid in U937 leukemia cells. Mutant Ski, lacking the N-CoR binding, was no more capable of repressing RARalpha signaling. The inhibition by wild-type Ski could partially be reverted by the histone deacetylase blocking agent valproic acid. In conclusion, Ski seems to be involved in the blocking of differentiation in AML via inhibition of RARalpha signaling.

[Targeted therapies in pediatric oncology: a new therapeutic approach?]

A multidisciplinary therapeutic approach has led to significant increase in survival of children with cancer, however often with a high rate of severe sequela. Better understanding in tumor cell biology and transformation process allowed to describe active tyrosine kinases (mainly growth factor receptors) as a new target for cancer treatment. This review presents 2 approaches to target receptor tyrosine kinase activity: on one hand, antibodies that target the extracellular domain, the natural ligand binding site, and on the other hand, small inhibiting molecules, such as imatinib, targeted against the activated intracellular receptor tyrosine kinase. We focus on their clinical development and current application in the treatment of childhood cancer. Targeted therapies are in full rise and new perspectives are explored, such as their association to other treatment modalities and the targeting of microenvironment. This new therapeutic approach necessitates well designed clinical trials that include relevant biomarkers to evaluate its real therapeutic potential.

Efficient ex vivo expansion of NOD/SCID-repopulating cells with lympho-myeloid potential in hematopoietic grafts of children with solid tumors

INTRODUCTION

The ex vivo expansion of hematopoietic grafts could be an important therapeutic tool for accelerating hematopoietic recovery after administration of high-dose chemotherapy regimens. The fate of the long-term repopulating cells during the ex vivo manipulation of grafts is a critical issue and will ultimately define the clinical applicability of this technology to hematopoietic transplantation.

MATERIALS AND METHODS

To study the effects of a clinically applicable ex vivo expansion protocol in the proliferative potential of the most primitive human hematopoietic cells, both LTC-IC and NOD/SCID-RC assays were used to determine LTC-IC and NOD/SCID-RC contents of hematopoietic grafts, both before and after expansion (SCF, IL-3, PEG-MGDF Flt3-L and 5% AB serum), in four children with non-hematological malignancies.

RESULTS

The mean percentage of CD34+ cells after expansion was 16%. The numbers of nucleated cells increased 20-fold with a mean three-fold increase in the numbers of CD34+ cells during the expansion period. The CFC content of the samples showed a mean 11-fold increase (range: 5-17) after ex vivo expansion. The primitive hematopoietic stem cell content of the expanded cell fraction evaluated by LTC-IC assays was found to be increased in two patients out of three, with maintenance of the LTC-IC frequency in the third patient. The NOD/SCID-RC potential, evaluated in five experiments from four patients using 109 mice injected 5-6 weeks earlier with human hematopoietic cells, increased from a mean percentage of 36% (range: 7-75%) before expansion, to a mean percentage of 70% (range: 37-100%) after expansion (P < 0.00001). The frequency of NOD/SCID-RC calculated with pooled data from all patients was 1/80,000 at day 0 and 1/40,000 after seven days of culture. The full phenotypic analysis of human hematopoietic cells obtained in NOD/SCID mice injected with expanded cells showed the presence of significant numbers of CD34+, CD19+ and CD15+ cells, suggesting the persistent lympho-myeloid potential of the expanded hematopoietic cells.

CONCLUSION

Our results suggest that efficient expansion of NOD/SCID-RC with lympho-myeloid potential can be achieved not only in cord blood or normal marrow as previously reported, but also in hematopoietic grafts obtained from children exposed to high-dose chemotherapy.

Ethical issues in pediatric oncology phase I-II trials based on a mother's point of view

Phase I-II trials are developing in Pediatrics and raise many complex relational, psychological and ethical issues. We present and discuss these based on an interview in a pediatric oncology setting, with a mother who accepted that her daughter be included in such trials and who expressed why she accepted with great sensitivity and profoundness. She explained that after many years of inefficient treatments she had lost all her landmarks and was ready to accept any proposition, even those she would have considered unacceptable earlier. She did not know whether there is a limit to what is acceptable. Her only objective was to gain any time possible in order to continue living with her daughter. She found it important that the research doctor be different from the doctor involved in patient care, and that the latter remains the major decision-maker and correspondent: thus the child's best interests take precedence over that of research. Interviews with the psycho-oncologist can help the parents and the doctors gain a better insight into the various aspects, rational and irrational, conscious and unconscious, involved in the proposition to participate in a clinical trial and in the parents' or the child's acceptance or refusal.

Les adolescents traités pour un cancer et la préservation de leur fertilité. Aspects psychologiques

Sperm preservation should be proposed to all the adolescents undergoing treatment for a cancer, because fertility is a major desire of young adults cured of a cancer. Proposing sperm preservation is among the oncologist's concerns about preventing sequels. However, this proposition can give rise to psychological problems as it concerns cancer and adolescence. For sperm collection to take place in a favourable climate with the adolescent's approval, their psychology and behaviour towards cancer should be well apprehended: they worry about their body, their appearance, their sexuality, their relations with their peers and their parents, their value, their narcissism, and their identity; but they can also be anxious, pessimistic about their future, disillusioned with parenthood, afraid of transmitting cancer, etc. Knowing these aspects helps one to understand and overcome any reluctance and to attenuate feelings of guilt and suffering in case of failure. Thus, a balance can be struck between overrespecting superficial opposition and imposing a decision that is not authentically theirs. In addition, closer relations nurtured between the sperm bank and oncohaematology departments, adolescent-friendly information material, and a better knowledge of adolescent psychology could also be helpful.

La tumeur d'Ewing

Ewing's tumor (ET) is a malignant bone tumor occurring in children and young adults. ET affects mainly bones of the central axis, and almost always involves soft tissue infiltration. The discovery of a unique genetic alteration, which is a reciprocal translocation most frequently resulting in the fusion of the EWS gene situated on chromosome 22 with the FLI-1 gene on chromosome 11, currently places ET among neuroectodermal tumors. Moreover, this translocation is a tumor-specific genetic marker at the basis of defining ET today and is used as a diagnostic and potentially prognostic tool complementary to imaging and histopathological work-up. Since the 1970 s, important progress has been made in the clinical management of ET patients. Multiagent chemotherapy in association with local treatment (surgery and/or radiation) has clearly improved outcome. The introduction of systemic treatment was justified by the frequent sub-clinical diffusion of apparently localized ET. Intensified therapeutic strategies have for the first time cured some metastatic ET patients, but at the cost of major side effects. Treatment is currently adapted as a result of a better definition of prognostic factors as well as a better assessment of its adverse effects. Improvement in global patient care and increased management of specific acute complications associated with ET (often interwoven with iatrogeneous effects) represent an important step towards improving the quality of life for ET patients as well as preventing long term complications. In the light of present studies, the majority of surviving adults today describe their health and quality of life as good. ET is a fascinating example of the progress made not only in the diagnostic and therapeutic approach to cancer but also in the comprehension of the mechanisms behind carcinogenesis, and consequently reflects the revolution of medicine over the last century.

Survey on haematopoietic stem cell transplantation for children in Europe

A recent report, prepared in March 2003, regarding the paediatric transplantation activity registered between 1970 and 2002 in the European Bone Marrow Transplantation (EBMT) database showed a decrease in the number of registrations in 2001 and in 2002. In order to validate this observation, the Paediatric Diseases Working Party (PDsWP) secretariat distributed a questionnaire to 395 institutions participating in the EBMT Registry. Each institution was requested to check the number of transplants they reported and to confirm or to correct the figures. As of 15 March 2004, replies had been received from 135 centres reporting a median of 48 transplants per centre over the study period, total 17 891 (58% of the total number). Among them, 55 confirmed their original figures, while 80 corrected the numbers. The overall number of autologous and allogeneic SCTs performed and not reported were 461 and 692, respectively. Most of the teams that corrected their figures stated that their data managers could provide missing data to the EBMT; 260 other teams, each reporting a median of 15 transplants during the study period, total 12 866 (42% of the total number) chose not to reply. A report prepared in March 2004, following the PDsWP survey, showed an increasing number of transplants performed on patients below 18 years of age between 1973 and 2002 and reported to the EBMT Registry (328 autologous and 628 allogeneic) as compared to the 2003 report. This first PDsWP survey, reaching more than 50% of activity in the field, illustrates that the decrease in activity we observed in the 2003 report does not correspond to a decrease in the number of transplants that were actually performed. It demonstrates the compliance of most major paediatric institutions and confirms the important role of cooperation between National Registries and EBMT Registries.

Quality control for microarray experiments

OBJECTIVES

In this paper we give an overview of post-hybridization quality control methods for gene expression chips, including methods for the gene/spot level, the hybridization/chip level and the process level. We present quality control methods that can be applied after hybridization and image analysis, i.e. that use data from the chip experiment itself. Wet lab quality control steps, which should be applied before the probe is measured on a chip, are not discussed. This review is aimed towards statisticians and data analysts.

METHODS

We give examples of some of the quality control measures available for spotted cDNA and Affymetrix GeneChips, the most common chip types. As quality control measures are technology and design-dependent, we will stress on methods that have the potential to be applied platform-independently.

RESULTS

Quality control should identify poor quality chips or hybridizations, as well as faulty measurements for individual genes/spots. Additionally, high throughput laboratories processing several tens or hundreds of microarrays per week have the need for an appropriate process control to be able to identify changes in the production process as early as possible.

CONCLUSION

Microarrays have become a standard research tool for biologists and medical researchers. As a consequence, there is a great need for standardized quality control, as false findings due to problem in data quality can lead to a substantial loss of resources.

Portal vein thrombosis during antineoplastic chemotherapy in children: Report of five cases and review of the literature

We report five paediatric cases of portal vein thrombosis (PVT) occurring during chemotherapy, observed in two institutions over an 8-year time period. These children aged 2.5-15 years were treated for Burkitt's lymphoma, Ewing's tumour, small cell bone tumour or medulloblastoma. PVT was diagnosed on colour Doppler ultrasonography (US). In four patients, thrombosis occurred 2-45 days after severe hepatic veno-occlusive disease (HVOD) secondary to intensive chemotherapy containing busulfan. In one case, PVT occurred in the absence of HVOD in a patient with pre-existing periportal lymphomatous infiltration. Four patients experienced persistent portal hypertension, which resulted in death in one. PVT during chemotherapy in children is a rare event and appears to be closely related to intensive chemotherapy containing busulfan and to be associated with HVOD.

Cardiac abnormalities 15 years and more after adriamycin therapy in 229 childhood survivors of a solid tumour at the Institut Gustave Roussy

The purpose of this paper was to determine the cardiac status in children 15 years or more after adriamycin therapy for a solid tumour. Of the 447 pts, 229 pts were fully studied and 218 were not. The following cardiac evaluations were proposed to all the 447 consecutive patients (pts): (1) cardiac Doppler US by one of two expert cardiologists; (2) cardiac rhythm and conduction abnormalities including 24-hour holter ECG; (3) (131)l-mlBG myocardial scintigraphy; (4) serum brain natriuretic peptide levels at rest; (5) an exercise test with VO(2) max measurement. The radiation doses delivered to 6 points in the heart were estimated for all patients who had received radiotherapy. Congestive heart failure was diagnosed in 24 of 229 (10%) evaluated pts, with a median interval of 15 years (0.3-24 years) from the first symptom after adriamycin treatment. Among the 205 remaining pts, 13 asymptomatic pts (6%) had severe (n=4) (FS<20%) or marked (n=9) (20< or =FS<25%) systolic dysfunction. In the 192 others, the median meridional end-systolic wall stress was 91 (53-135) and it exceeded 100 g cm(-2) in 52 pts. Using a Cox model, only the cumulative dose of adriamycin and the average radiation dose to the heart, were identified as risk factors for a pathological cardiac status. In conclusion, the risk of cardiac failure or severe abnormalities increases with adriamycin treatment, radiotherapy and time since treatment, even after a follow-up of 15 years or more. In our series, after an average follow-up of 18 years, 39% of the children had a severe cardiac dysfunction or major ventricular overload conditions. The risk increases with the dose of adriamycin and radiation received to the heart, without evidence for threshold.

Candida infections in children treated with conventional chemotherapy for solid tumors (transplant recipients excluded): The Institut Gustave Roussy Pediatrics Department experience

INTRODUCTION

Advances in medical therapy have greatly improved the survival of children suffering from cancer. Although progress has been made in the eradication of malignant disease there is growing concern for the development of fungal infections in patients treated with chemotherapy.

MATERIALS AND METHODS

We reviewed all episodes of pediatric candidemia that occurred between January 1988 and December 2000. We analyzed the general characteristics of this population, risk factors, microbiology features, treatment, complications, and outcome.

RESULTS

Seventeen cases of candidemia were observed during the 12 years of the study at an estimated incidence of 0.4%. Neutropenia occurred at the onset of infection in 13/17 (76.5%) children. A central venous device was present in all cases. Seventy-seven percent of the infections were caused by Candida albicans and in 85% of patients, yeasts had colonized the gastrointestinal tract. In 9/17 patients visceral dissemination was documented. Overall, in 77% of the episodes the outcome was favorable.

CONCLUSIONS

Candidemia is a rare but severe complication in pediatric oncology. Even if the prognosis is better in children than in adults, Candida septicemia remains of great concern since a high percentage of these infections result in visceral dissemination and mortality is still elevated.

Outcome of flat bone sarcomas (other than Ewing's) in children and adolescents: a study of 25 cases

We analysed the clinical features and outcome of young patients with non-Ewing's flat bone sarcoma treated during the era of contemporary chemotherapy. The characteristics and outcome of 25 patients (15 males and 10 females) with primary or radiation-related flat bone sarcoma treated in the Pediatrics Department at the Institut Gustave Roussy from 1981 to 1999 were reviewed. In all, 20 patients had osteosarcoma, four chondrosarcoma and one malignant fibrous histiocytoma. The age at diagnosis ranged from 2 to 23 years (median, 15 years). Nine tumours were located in the craniofacial bones, 11 in the pelvis and five in flat bones at other sites. Four patients had metastatic disease at diagnosis. Radiation-associated flat bone osteosarcoma was diagnosed in 10 out of 25 cases. The projected overall survival and event-free survival (EFS) rates at 5 years were 45.1 and 34.3% for all the 25 patients. The EFS rate of patients with second bone sarcoma was similar to that of patients with de novo flat bone sarcoma (P=0.1). The aim of treatment was curative for 24 patients, 23 of whom were treated with intensive chemotherapy regimens and 19 with surgery. Significant adverse prognostic factors on survival included incomplete surgical resection (P=0.001) and use of regimens without pre- and postoperative chemotherapy (P=0.007). Nine of the 25 patients were treated with pre- and postoperative chemotherapy and complete surgical resection. Among them, eight are alive with no disease. Radical surgical resection is the overriding prognostic factor for flat bone sarcomas in young patients. Nevertheless, our results suggest a more favourable outcome since the advent of intensive chemotherapy.