Recurrent noncoding U1 snRNA mutations drive cryptic splicing in SHH medulloblastoma.

In cancer, recurrent somatic single-nucleotide variants-which are rare in most paediatric cancers-are confined largely to protein-coding genes1-3. Here we report highly recurrent hotspot mutations (r.3A>G) of U1 spliceosomal small nuclear RNAs (snRNAs) in about 50% of Sonic hedgehog (SHH) medulloblastomas. These mutations were not present across other subgroups of medulloblastoma, and we identified these hotspot mutations in U1 snRNA in only <0.1% of 2,442 cancers, across 36 other tumour types. The mutations occur in 97% of adults (subtype SHHδ) and 25% of adolescents (subtype SHHα) with SHH medulloblastoma, but are largely absent from SHH medulloblastoma in infants. The U1 snRNA mutations occur in the 5' splice-site binding region, and snRNA-mutant tumours have significantly disrupted RNA splicing and an excess of 5' cryptic splicing events. Alternative splicing mediated by mutant U1 snRNA inactivates tumour-suppressor genes (PTCH1) and activates oncogenes (GLI2 and CCND2), and represents a target for therapy. These U1 snRNA mutations provide an example of highly recurrent and tissue-specific mutations of a non-protein-coding gene in cancer.

Management experience of pediatric meningioma in a Mexican reference center.

OBJECTIVE: Determine the histopathological and clinical characteristics of patients diagnosed with meningiomas and to establish the frequency of these tumors in the pediatric population Mexican. Determine the NF1/2 frequency in meningioma pediatric. METHODS: Samples from the histopathology file were reviewed, and from the complete clinical file the following patient data was reviewed: age, gender, diagnosis, diagnosis year, surgical resection, location, tumor size, symptoms, and family background. The frequency of NF1/2 in pediatric meningioma was reviewed in literature. RESULTS: Forty-four de novo cases were collected from pediatric patients; 19 were female patients and 25 males. The most frequent histological subtype was transitional meningioma. Of all the cases, 75% had a supratentorial localization and 20% had an extramedullary intrarachidian localization. Some clinical manifestations included seizures, paresis, headache, and visual disturbances. CONCLUSION: There is a low incidence of meningiomas in the pediatric population, more than 70% are Grade I, and they have supratentorial localization.

Predictors of anthracycline-induced cardiotoxicity in a retro-prolective cohort of children surviving cancer.

INTRODUCTION: Cardiotoxicity is an adverse reaction associated with the use of anthracyclines. OBJECTIVE: To estimate the factors associated with the development of anthracycline cardiotoxicity in pediatric patients surviving cancer. METHOD: Retro-prolective cohort of children diagnosed with cancer and treated with anthracyclines. Baseline echocardiographic determination of ejection fraction (LVEF0) was carried out before the start of treatment and again at 12 months (LVEF1). Demographic characteristics and treatment were obtained from the medical record. A multiple logistic regression (MLR) model was constructed; LVEF1 < 50 % was the dependent variable, which was adjusted for the main confounding variables. RESULTS: Sixty-five patients were included, out of which 36.9 % were females and 56.8 % had a solid tumor. LVEF0 was 74.79 ± 7.3 % and LVEF1, 67.96 ± 6.7 % (p = 0.001); 60 % developed cardiotoxicity. In the MLR, only a cumulative dose > 430 mg was associated with cardiotoxicity (p = 0.001). CONCLUSIONS: In Mexican children, an anthracycline cumulative dose > 430 mg should be avoided in order to prevent cardiotoxicity.

INTRODUCCIÓN: La cardiotoxicidad es una reacción adversa asociada al uso de antraciclinas. OBJETIVO: Estimar los factores asociados al desarrollo de cardiotoxicidad por antraciclinas en pacientes pediátricos supervivientes de cáncer. MÉTODO: Cohorte retroprolectiva de niños con diagnóstico de cáncer tratados con antraciclinas. Se realizó determinación ecocardiográfica basal de la fracción de expulsión (FEVi0) antes del inicio del tratamiento y a los 12 meses (FEVi1). Del expediente se obtuvieron las características demográficas y el tratamiento. Se realizó un modelo de regresión logística múltiple (RLM); la FEVi1 < 50 % fue la variable dependiente, que se ajustó por las principales variables confusoras. RESULTADOS: Se incluyeron 65 pacientes, 36.9 % fue del sexo femenino y 56.8 % presentó un tumor sólido. La FEVi0 fue de 74.79 ± 7.3 % y la FEVi1, de 67.96 ± 6.7 % (p = 0.001); 60 % desarrolló cardiotoxicidad. En la RLM solo la dosis acumulada > 430 mg se asoció a cardiotoxicidad (p = 0.001). CONCLUSIONES: En los niños mexicanos se debe evitar una dosis acumulada > 430 mg de antraciclinas para evitar la cardiotoxicidad.

Diagnostics and treatment of diffuse intrinsic pontine glioma: where do we stand?

INTRODUCTION: Diffuse intrinsic pontine glioma (DIPG) is a rare clinically, neuro-radiologically, and molecularly defined malignancy of the brainstem with a median overall survival of approximately 11 months. Our aim is to evaluate the current tendency for its treatment in Europe in order to develop (inter)national consensus guidelines. METHODS: Healthcare professionals specialized in DIPG were asked to fill in an online survey with questions regarding usual treatment strategies at diagnosis and at disease progression in their countries and/or their centers, respectively. RESULTS: Seventy-four healthcare professionals responded to the survey, of which 87.8% were pediatric oncologists. Only 13.5% of the respondents biopsy all of their patients, 41.9% biopsy their patients infrequently. More than half of the respondents (54.1%) treated their patients with radiotherapy only at diagnosis, whereas 44.6% preferred radiotherapy combined with chemotherapy. When the disease progresses, treatment strategies became even more diverse, and the tendency for no treatment increased from 1.4% at diagnosis to 77.0% after second progression. 36.5% of the healthcare professionals treat children younger than 3 years differently than older children at diagnosis. This percentage decreased, when the disease progresses. Most of the participants (51.4%) included less than 25% of their patients in clinical trials. CONCLUSION: This survey demonstrates a large heterogeneity of treatment regimens, especially at disease progression. We emphasize the need for international consensus guidelines for the treatment of DIPG, possible by more collaborative clinical trials.

Adipokines, insulin resistance, and adiposity as a predictors of metabolic syndrome in child survivors of lymphoma and acute lymphoblastic leukemia of a developing country.

BACKGROUND: There is a growing body of evidence indicating that pediatric survivors of cancer are at a greater risk of developing metabolic syndrome. This study evaluated some probable predictors of metabolic syndrome (MS), such as leptin and adiponectin concentrations, the leptin/adiponectin ratio, insulin resistance, and adiposity, in a sample of child survivors of lymphoma and leukemia in Mexico City. METHODS: Fifty two children (leukemia n = 26, lymphoma n = 26), who were within the first 5 years after cessation of therapy, were considered as eligible to participate in the study. Testing included fasting insulin, glucose, adipokines and lipids; body fat mass was measured by DXA. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. Comparisons between continuous variables were performed according to the data distribution. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. With the purpose of assessing the risk of a present MS diagnosis, odds ratios (OR) with a 95% confidence interval (95% IC) were obtained using logistic regression analysis according to the various metabolic markers. RESULTS: The median children age was 12.1 years, and the interval time from the completion of therapy to study enrollment was 4 years. Among the MS components, the prevalence of HDL-C low was most common (42%), followed by central obesity (29%). The HOMA-IR (OR 9.0, 95% CI 2.0; 41.1), body fat (OR 5.5, 95% CI 1.6; 19.3), leptin level (OR 5.7, 95% CI 1.6; 20.2) and leptin/adiponectin ratio (OR 9.4, 95% CI 2.0; 49.8) in the highest tertile, were predictive factors of developing MS; whereas the lowest tertile of adiponectin was associated with a protective effect but not significant. CONCLUSIONS: Biomarkers such as HOMA-IR, leptin and leptin/adiponectin are associated with each of the components of the MS and with a heightened risk of suffering MS among children survivors of cancer. Given the close relationship between MS with risk of developing type 2 diabetes and cardiovascular disease, it is imperative to implement prevention measures in this population and especially in developing countries where these pathologies have become the leading cause of death.

Unsuspected Lung Pathology in Autopsies of Children with Cancer.

BACKGROUND: Although pulmonary involvement is common in patients with cancer, its frequency and nature is seldom reported in the medical literature. OBJECTIVE: To determine the frequency and type of lung pathological conditions revealed by autopsy in children with cancer. METHODS: All reports from autopsies performed in children with cancer from 1989 to 2012 in a pediatric hospital were reviewed. RESULTS: In the analyzed period, 118 autopsies (10.2% of all autopsies) corresponded to children who died with cancer; 76 had complete information and were included in the analysis. Children were seen in the Hematology (41 cases) or the Oncology (35 cases) services. Their median age at decease was 7 years (range, 15 days to 16.1 years) and 46.1% were females. Main diagnoses were acute lymphoblastic (31 patients) or myeloblastic (10 patients) leukemias and tumors of the central nervous system (12 patients). A pathological respiratory condition was diagnosed antemortem in 31 (40.8%) patients, and at autopsy in 62 (81.6%) cases. Omitted diagnoses occurred in 58 (76.3%) children, being pneumonia (24 cases) and pulmonary hemorrhage (23 cases) the most frequent omissions. Nine patients had clinically unsuspected tumor infiltration or metastases. CONCLUSIONS: In these children with cancer, more than 80% of autopsies revealed some lung pathology, mainly of infectious or hemorrhagic nature. Thus, pulmonary involvement should be investigated in all children with cancer in a timely and intentional manner.

Risk Factors for Febrile Neutropenia in Children With Solid Tumors Treated With Cisplatin-based Chemotherapy.

Febrile neutropenia (FN) is a common and potentially fatal adverse drug reaction of cisplatin-based chemotherapy (CDDPBC) in pediatric patients. Hence, the aim of this study was to determine the incidence and independent risk factors for FN in pediatric patients with solid tumors treated with CDPPBC. Cohort integration was performed in the first cycle of chemotherapy with CDDPBC and patients were followed up to 6 months after the last cycle. FN was defined according to the Common Terminology Criteria for Adverse Events. Relative risks were calculated with confidence intervals at 95% (95% CI) to determine FN risk factors. Multiple logistic regression was performed to identify independent risk factors. One hundred and thirty-nine pediatric patients (median age 7.4 y, range 0.08 to 17 y) were included in the study. FN incidence was 62.5%. Independent risk factors for FN were chemotherapy regimens including anthracyclines (odds ratio [OR]=19.44 [95% CI, 5.40-70.02), hypomagnesaemia (OR=8.20 [95% CI, 1.81-37.14]), and radiotherapy (OR=6.67 [95% CI, 1.24-35.94]). It is therefore concluded that anthracyclines-containing regimens, hypomagnesaemia, and radiotherapy are independent risk factors for FN in patients receiving CDDPBC.

Onychomycosis in immunosuppressed children receiving chemotherapy.

Onychomycosis in children has a low incidence worldwide; certain conditions such as immunosuppression have been described as risk factors for it. We studied 72 children receiving chemotherapy for different neoplasms to determine the frequency of onychomycosis. Only one patient had white superficial onychomycosis from Trichophyton rubrum, a frequency of 1.3%, not different from that reported in healthy patients.

Subclassification of B-acute lymphoblastic leukemia according to age, immunophenotype and microenvironment, predicts MRD risk in Mexican children from vulnerable regions.

Introduction: The decisive key to disease-free survival in B-cell precursor acute lymphoblastic leukemia in children, is the combination of diagnostic timeliness and treatment efficacy, guided by accurate patient risk stratification. Implementation of standardized and high-precision diagnostic/prognostic systems is particularly important in the most marginalized geographic areas in Mexico, where high numbers of the pediatric population resides and the highest relapse and early death rates due to acute leukemias are recorded even in those cases diagnosed as standard risk. Methods: By using a multidimensional and integrated analysis of the immunophenotype of leukemic cells, the immunological context and the tumor microenvironment, this study aim to capture the snapshot of acute leukemia at disease debut of a cohort of Mexican children from vulnerable regions in Puebla, Oaxaca and Tlaxcala and its potential use in risk stratification. Results and discussion: Our findings highlight the existence of a distinct profile of ProB-ALL in children older than 10 years, which is associated with a six-fold increase in the risk of developing measurable residual disease (MRD). Along with the absence of CD34+ seminal cells for normal hematopoiesis, this ProB-ALL subtype exhibited several characteristics related to poor prognosis, including the high expression level of myeloid lineage markers such as MPO and CD33, as well as upregulation of CD19, CD34, CD24, CD20 and nuTdT. In contrast, it showed a trend towards decreased expression of CD9, CD81, CD123, CD13, CD15 and CD21. Of note, the mesenchymal stromal cell compartment constituting their leukemic niche in the bone marrow, displayed characteristics of potential suppressive microenvironment, such as the expression of Gal9 and IDO1, and the absence of the chemokine CXCL11. Accordingly, adaptive immunity components were poorly represented. Taken together, our results suggest, for the first time, that a biologically distinct subtype of ProB-ALL emerges in vulnerable adolescents, with a high risk of developing MRD. Rigorous research on potential enhancing factors, environmental or lifestyle, is crucial for its detection and prevention. The use of the reported profile for early risk stratification is suggested.

[Survival of patients with malignant astrocytomas according to the expression of Ki67 antigen in a pediatric hospital]. / Sobrevida de los pacientes con astrocitoma de alto grado que expresan el antígeno Ki67, atendidos en un hospital de pediatría.

BACKGROUND: Pediatric patients with malignant gliomas and same histological diagnosis respond distinctly to treatment. It is thus necessary to determine other factors that may influence the response to treatment and survival. Over expression of the Ki67 protein has been associated with poor treatment response. The aim of this study was to determine if the expression of this antigen influences survival of patients treated for malignant gliomas in the CMN SXXI Pediatrics Hospital. METHODS: We included patients with anaplasic astrocitoma or glioblastoma multiforme seen at our hospital between 1995 and 2005. We determined the expression of Ki67 by immunohistochemistry and correlated the findings with tumor histology and patient survival. RESULTS: Of the 21 patients studied, 12 overexpressed antigen Ki67. There was no significant association between over expression of Ki67 and survival, although we observed a clinical association. Over expression of Ki67 correlated with more aggressive histology. Being under the age of 11 was a poor prognostic factor. Overall survival was 49% at 120 months. CONCLUSIONS: Being young (under 11 years) is a marker of poor prognosis among pediatric patients with anaplasic astrocytoma or glioblastoma multiforme. Overexpression expression of antigen Ki67 is associated with histology and may be associated with poor survival among patients treated in our hospital.

Pattern of Relapse and Treatment Response in WNT-Activated Medulloblastoma.

Over the past decade, wingless-activated (WNT) medulloblastoma has been identified as a candidate for therapy de-escalation based on excellent survival; however, a paucity of relapses has precluded additional analyses of markers of relapse. To address this gap in knowledge, an international cohort of 93 molecularly confirmed WNT MB was assembled, where 5-year progression-free survival is 0.84 (95%, 0.763-0.925) with 15 relapsed individuals identified. Maintenance chemotherapy is identified as a strong predictor of relapse, with individuals receiving high doses of cyclophosphamide or ifosphamide having only one very late molecularly confirmed relapse (p = 0.032). The anatomical location of recurrence is metastatic in 12 of 15 relapses, with 8 of 12 metastatic relapses in the lateral ventricles. Maintenance chemotherapy, specifically cumulative cyclophosphamide doses, is a significant predictor of relapse across WNT MB. Future efforts to de-escalate therapy need to carefully consider not only the radiation dose but also the chemotherapy regimen and the propensity for metastatic relapses.

Epidemiological and some clinical characteristics of neuroblastoma in Mexican children (1996-2005).

BACKGROUND: Neuroblastoma (NB) is the principal tumor of the sympathetic nervous system in children under one year of age. The incidence in developed countries is greater than that in developing countries. The aim of this article is to present the epidemiological and some clinical characteristics of Mexican children with NB. METHODS: A population-based, prolective study, with data obtained from the Childhood Cancer Registry of the Instituto Mexicano de Seguro Social. STATISTICAL ANALYSIS: The simple frequencies of the variables of the study and the annual average incidence (per 1,000,000 children/years) by age and sex were obtained. The trend was evaluated by calculating the annual percentage of change. The curves of Kaplan-Meyer were employed for the survival rate and the log-rank test was used to compare the curves. RESULTS: Of a total of 2,758 children with cancer registered during the period from 1996-2005, 72 (2.6%) were identified as having Group IV, defined according to the International Classification of Childhood Cancer. The incidence for NB was 3.8 per 1,000,000 children/year; NB was highest in the group of children under one year of age, followed by the group of children between the ages 1-4 years (18.5 and 5.4 per 1,000,000 children/years, respectively). The male/female ratio was 1.1 and there was no trend toward an increase. The time of diagnosis was 26 days (median), but varied according to the stage at diagnosis. Stages III and IV were presented in 88% of the cases. There was no association between the stage, the age at time of diagnosis, or the histological pattern. The overall five-year survival rate was 64%; the patients with stage I, II, III, or IVs did not die; and the five-year survival rate of cases in Stage IV was 40%. CONCLUSION: It is possible that the low incidence of neuroblastoma in Mexican children is due to the difficulty in diagnosing the cases with the best prognosis, some of which could have had spontaneous regression. There was no trend to an increase; the majority of the cases were diagnosed in the advanced stages; and the overall five-years survival rate was similar to that for developed countries.

[Prognostic and survival factors among pediatric patients with ependymomas]. / Factores pronósticos y sobrevida de pacientes pediátricos con ependimomas.

BACKGROUND: Ependymomas constitute the third most common intracranial tumors in children. Risk factors include age, location, extent of surgical excision, and radiation therapy. Recently, chromosomal imbalances have been described. OBJECTIVE: Determine global survival of patients with ependymomas according to different prognostic factors. METHODS: We reviewed the medical charts of every pediatric patient with ependymoma from 1996 to 2005. Genomic imbalances were determined using comparative genomic hybridization (CGH). Survival was calculated using the Kaplan and Meier method. We used the Log Rank test for each risk factor. Death risk was calculated by odds ratio (OR). RESULTS: We included 24 patients. Global survival was 58.04%. The presence of chromosomal imbalances, particularly in chromosome 21, significantly affected survival Being under 5 years of age, anaplastic histology, chemotherapy other than ICE (ifosfamida-carboplatin-etoposide) and partial resection increased the risk of death. CONCLUSIONS: Known risk factors were confirmed in our study, including chromosomal imbalances. We describe a new chromosomal imbalance in chromosome 21 among 30% of study participants.

Nutritional status and cytokine concentration during chemotherapy in Mexican children: A longitudinal analysis.

OBJECTIVE: The aim of this study was to assess whether the nutritional status of children with cancer is influenced by variations in cytokine concentrations observed during chemotherapy. We also evaluated whether this relationship could be modified by nutritional status at diagnosis and type of cancer. METHODS: Mexican children with lymphoma or solid tumors were evaluated at diagnosis and at 2- and 6-mo follow-up visits. Blood samples were obtained to determine serum prealbumin, tumor necrosis factor (TNF)-α, interleukin (IL)-6, leptin concentrations, and hemoglobin. Children were classified as undernourished (UN) or well nourished (WN), according to prealbumin concentration. The influence of each cytokine on prealbumin concentration was analyzed by time-series regression model. RESULTS: Fifty patients (ages 2-17 y) were enrolled. There were 17 children with lymphomas and 33 with solid tumors. At baseline, 56% were UN and 26% presented anemia; the frequencies of UN children were higher for those with lymphoma than for those with a solid tumor (P = 0.003). By nutritional status, UN children presented lower leptin (P = 0.002) but higher IL-6 concentrations (P = 0.009) than the WN group. Children with lymphoma presented lower prealbumin (P = 0.003), but higher TNF-α (P = 0.001) and IL-6 (P = 0.011) concentrations than those with solid tumors. At follow-up, the concentration of prealbumin increased and IL-6 decreased in children with lymphoma. Multivariate analysis demonstrated that decreases in prealbumin concentration at the end of follow-up were associated with increases in IL-6 and TNF-α concentration during chemotherapy. CONCLUSIONS: These results suggest that the cytokine responses during chemotherapy are related to nutritional status at the end of 6 mo of treatment regardless of the initial nutritional status and the type of cancer.

Palonosetron hydrochloride is an effective and safe option to prevent chemotherapy-induced nausea and vomiting in children.

BACKGROUND: Emesis and nausea are common adverse effects of chemotherapy. Consequences include dehydration, acute renal failure, esophageal rupture, electrolyte imbalance and undernutrition, among others. First-generation 5-HT3 antagonists significantly reduce these symptoms but are expensive and require administration every 8-12h. Palonosetron, a second generation 5-HT3 antagonist has proven better results in adult populations. Other benefits include a one-dose administration with effect for up to 7 days and a lower treatment cost. No clinical studies have evaluated the safety and efficacy of palonosetron in children. METHODS: Prior to every course, patients were randomized to receive palonosetron or ondansetron. Patients or guardians recorded the number of emetic events and the intensity of nausea over a 7-day period. They also reported any possible adverse effects. Statistical analysis included chi(2) test, relative risk, and Student's t test. RESULTS: Fifty courses were analyzed for each group. There was a significant reduction in emesis on the first 3 days and in the intensity of nausea in the first four days in the palonosetron group. There was an increased risk of presenting emesis and nausea in the acute phase when treated with ondansetron. No adverse effects were reported. The cost of treatment was also reduced when using palonosetron. CONCLUSIONS: Palonosetron is a safe and effective antiemetic treatment in children, as well as being cost effective.

Phase II study of metronomic chemotherapy with thalidomide, carboplatin-vincristine-fluvastatin in the treatment of brain stem tumors in children.

BACKGROUND: Brain stem tumors (BST) constitute 20% of all intracranial tumors. Survival for these patients has been very poor worldwide. Four different treatment schemes have been evaluated at our institution, with only a discrete increment in survival when treated with carboplatin-vincristine and fluvastatin (CVF). Low-dose, continuous antiangiogenic treatment has been recently introduced in the treatment of cancer. Our objective was to determine tumor response to metronomic chemotherapy combined with an antiangiogenic drug and fluvastatin and to calculate the survival of pediatric patients with brain stem tumors. METHODS: This was a phase II study. A magnetic resonance (MRI) study was made at inclusion and after the fourth course. Routine laboratory analyses were performed prior to each treatment scheme. Patients received four courses of chemotherapy every 28 days consisting of thalidomide alternating with fluvastatin every 14 days and combined with carboplatin and vincristine every 14 days followed by radiotherapy (56 cGy) and four more courses of the same chemotherapy. Toxicity was evaluated according to Miller criteria. RESULTS: Nine recently diagnosed BST patients were included. Five patients had low-grade astrocytomas, three patients had glioblastoma multiforme, and one patient presented high-grade astrocytoma. There was a significant reduction in tumor volume and a significant increase in survival at 24 months. Two patients died. Toxicity included carboplatin allergy in one patient, grades 1 and 3 neutropenia in two patients, and grade 4 thrombocytopenia in two patients. CONCLUSIONS: Metronomic treatment with carboplatin and vincristine associated with fluvastatin and thalidomide significantly increased survival of pediatric brain stem tumor patients. Tumor volume showed a significant reduction. Quality of life was also increased. Sample size must be increased in order to make final conclusions.

Gene expression profiling from formalin-fixed paraffin-embedded tumors of pediatric glioblastoma.

PURPOSE: Gene expression profiling has proved crucial for understanding the biology of cancer. In rare diseases, including pediatric glioblastoma (pGBM), the lack of readily available fresh frozen (FF) material limits the feasibility of this analysis, as well as its validation, on independent data sets, a step needed to ensure relevance, mandating the use of alternate RNA sources. To overcome the limitation of material number and to validate results we obtained on FF pGBM, we did microarray analysis on RNA extracted from formalin-fixed, paraffin-embedded archival samples from pGBM and control brains, wherein we had no control on the fixation process. EXPERIMENTAL DESIGN: RNA from 16 pGBM and 3 control brains was extracted and linearly amplified. Reverse transcription-PCR on housekeeping and formerly identified tumor-associated genes and microarray analysis were done on this RNA source. Results were validated by immunohistochemistry. RESULTS: Despite extensive RNA degradation, microarray analysis was possible on 16 of 19 samples and reproduced the pattern of results obtained on FF pGBM. Gene lists and ontology subgrouping were highly concordant in both sample types. Similar to the findings on FF samples, we were able to identify two subsets of pGBM based on their association/lack of association with evidence consistent with an active Ras pathway. CONCLUSIONS: Archival formalin-fixed, paraffin-embedded tissues are an invaluable resource as they are the most widely available materials often accessible in conjunction with clinical and follow-up data. Gene expression profiling on this material is feasible and may represent a significant advance for understanding the biology of rare human diseases.

Clinical and molecular parameters for risk stratification in Mexican children with medulloblastoma.

BACKGROUND: Clinical, histological, and more recently, molecular factors have been described as important in survival of the patient with medulloblastoma. Best survival results include aggressive chemotherapeutic protocols. More exact risk analysis may differentiate patients who require aggressive treatments from those with low risk who may respond adequately to less aggressive protocols. METHODS: Twenty six patients were included over a 10-year period and were followed for at least 5 years. Personal variables were obtained from their clinical records. Immunochemistry studies were performed on their formalin-fixed paraffin-embedded tissues. Statistical analysis included chi(2) test, odds risk, linear regression models, and Kaplan-Meier survival analysis. RESULTS: Metastatic disease and chemotherapy with VP16-carboplatin reduce the patient's probability of survival, whereas anaplastic histology increases the probability of death. Global survival and disease-free survival were 66.6 and 45.02%, respectively. Only two patients overexpressed the ERBB2 protein, and no significant difference was found in survival in terms of ERBB2 overexpression. CONCLUSIONS: Risk stratification has become very important in medulloblastoma. We found an increased hazard of death when metastatic disease was present. Gene expression in Mexican children requires a larger sample in order to be analyzed.

Body composition by dilution of deuterium oxide in Mexican children with lymphoma and solid tumors.

OBJECTIVE: Scant information exists about the changes in body composition of children during the first months of chemotherapy. These changes can be determined by using a better method than the body mass index. This study compared the changes of body composition by dilution of deuterium oxide in Mexican children with lymphoma and with solid tumors. METHODS: Seventeen patients were enrolled and classified as having lymphoma or solid tumor. Body composition was measured by a deuterium dilution technique after the first course of chemotherapy and again after 2 and 6 mo of therapy. Data were compared by means of paired t and Student's t tests. Simple linear regression was applied to examine the relation between age and changes in fat mass (FM) and fat-free mass (FFM). RESULTS: The groups were similar at baseline. Six months after initiation of chemotherapy, weight and height had increased (P < 0.05) in the lymphoma group, whereas only height had increased in the solid-tumor group; total body water, FM, and FFM increased in the lymphoma group (P < 0.01) but not in the solid-tumor group. Age did not influence FM or FFM in either group. CONCLUSION: In children with lymphoma whose treatment included corticosteroid use, increase in FM content was demonstrated during the first 6 mo of treatment. In patients with solid tumors, FM content did not change during treatment. With an increase in FM content, one should bear in mind that overweight and obesity may result in cardiovascular disease and development of breast cancer in adult life.