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Biomedical subjects

Raul C Ribeiro

Publications and source records attributed to Raul C Ribeiro.

At least 19 recordsLinked to original sources
PubMed2007

Prognostic factors and outcome of recurrence in childhood acute myeloid leukemia.

BACKGROUND: Outcome after recurrence of childhood acute myeloid leukemia (AML) is poor. We performed this study to identify prognostic factors for recurrence and for survival after recurrence of AML. METHODS: The clinical characteristics, biological features, treatment modalities, and outcomes of children with de novo AML who were enrolled on 3 consecutive clinical protocols from 1987 to 2002 at St. Jude Children's Research Hospital were studied. Regression modeling was used to identify prognostic factors for recurrence and for survival after recurrence. RESULTS: The outcome after recurrence was poor, with a 5-year survival estimate of only 23.3% +/- 5.7%. Multivariable analysis indicated that male sex (P = .005), autologous stem cell transplant before recurrence (P = .097), each additional month from diagnosis to recurrence (P = .041), and stem cell transplant after recurrence (P < .001) were associated with a better survival after recurrence, whereas M5 or M7 morphology (P = .001) were significantly predictive of a lower survival estimate after recurrence. CONCLUSIONS: Survival after recurrence was poor in children with AML. Novel therapies are urgently needed to prevent or to treat recurring AML.

Acute Disease↗
PubMed2007

Effect of race on outcome of white and black children with acute myeloid leukemia: the St. Jude experience.

BACKGROUND: The association between race and outcome of treatment for childhood acute myeloid leukemia (AML) has not been adequately studied. PROCEDURE: We compared the clinical characteristics, biological features, and outcomes between white and black children with AML who were treated on five consecutive clinical protocols (1980-2002) at St. Jude Children's Research Hospital. We used proportional hazards modeling to investigate the relation between race and outcome. RESULTS: We observed no statistically significant differences between the 229 white and 58 black patients in clinical characteristics, FAB subtype, cytogenetic features, or outcome. There were no significant differences in event-free survival (EFS) or overall survival (OS) between the two race groups in individual clinical trials or in all studies combined. For the study group as a whole, the 5-year survival estimate was 39.2% +/- 3.6% for white patients and 33.8% +/- 6.5% for black patients. However, on our most recent trial (AML-97), there was a trend towards inferior outcome among black patients: the 5-year survival estimates were 55.6% +/- 12.3% and 27.3% +/- 13.5% for whites and blacks, respectively. CONCLUSIONS: Although we detected no differences in treatment outcome between white and black children with AML over the entire study period, black children appear to have worse outcomes than white children during more recent studies. Improved treatment is needed for all children with AML.

Adolescent↗
PubMed2007

Comparison of treatment outcomes of childhood Hodgkin lymphoma in two US centers and a center in Recife, Brazil.

BACKGROUND: Pediatric Hodgkin lymphoma (HL) has a cure rate of more than 80% in high-income countries (HIC). However, more than 80% of the world's children live in low-income countries (LIC), where the cure rate is often much lower. PROCEDURE: We compared the outcome of HL of 371 patients treated at two pediatric oncology centers in the US to that of 62 patients treated at one center in Recife, Brazil (IMIP) to determine whether the same treatment strategy should be used in both high-income and LIC. The logrank test was used to compare event-free and overall survival. RESULTS: The percentages of patients with unfavorable disease at each center were similar (P = 0.72). Patients with favorable disease at IMIP had estimated 5-year survival rates comparable to those of the US centers (100% and 99%, respectively). Among patients with unfavorable disease, those treated at IMIP had a 5-year event-free survival (EFS) rate of 60%, compared to 78% at the US centers; (P = 0.08). The 5-year survival estimate after relapse was 25% at IMIP versus 61% at the US centers (P = 0.08). The 5-year overall survival for patients with unfavorable disease was 72% at IMIP versus 90% at the US centers (P = 0.01). CONCLUSIONS: Intensive frontline therapy should be considered for patients with unfavorable HL in LIC where the relapse rate is high and the salvage rate is low, provided that supportive care is adequate.

Adolescent↗
PubMed2007

Implementation of a data management program in a pediatric cancer unit in a low income country.

INTRODUCTION: Pediatric cancer units in low-income countries lack data on which to base quality improvement initiatives. We implemented a data management program in the oncology unit of the children's hospital of Tegucigalpa, Honduras, and then we assessed training and supervision of data managers, data accuracy, and completeness as well as obstacles encountered. METHODS: Training included 2 days of off-site hands-on instruction in the use of an online database, daily on-site supervision by physicians, periodic online meetings for education and problem-solving, and continuous e-mail support. RESULTS: Of the 652 patients diagnosed with acute leukemia between July 1995 and June 2005, 150 (23%) had not yet been registered in the database at the time of audit and 65 (10%) had missing medical records. The remaining 437 charts (67%) were reviewed by an external auditor and compared to the data entered previously by the two trained data managers. Protocol information was incomplete in 30% of cases, and the cause of death was inaccurate in 18%. All other data were 99% accurate and 93%-100% complete. Obstacles included a limited medical records system, poor organization of the charts, missing records, inconsistently documented protocol information, data managers who lack a medical background, and slow or unreliable internet connections. CONCLUSION: Data managers can be trained to effectively collect basic pediatric oncology data in a low-income country. Addressing inadequacies in the medical record system while providing specific training in protocol-based care and determination of cause of death for both physicians and data managers will improve data quality.

Clinical Protocols↗
PubMed2007

Improving outcomes for children with cancer in low-income countries in Latin America: a report on the recent meetings of the Monza International School of Pediatric Hematology/Oncology (MISPHO)-Part I.

The difference in survival for children diagnosed with cancer between high- and low-income countries (LIC) continues to widen as curative therapies are developed in the former but not implemented in the latter. In 1996, the Monza International School of Pediatric Hematology/Oncology (MISPHO) was founded in an attempt to narrow this survival gap. During its sixth and seventh meetings, members recognized the problem of lack of affordability of essential drugs to treat childhood cancer in many LIC, and initiated an advocacy program. In 1998, MISPHO spawned a collaboration of Central American pediatric oncology centers: the Asociación de Hemato-Oncología Pediátrica Centroamericana (AHOPCA). AHOPCA members reported preliminary findings from several of the 10 cooperative protocols that are currently in progress. In 2003, a second regional collaborative group was formed that includes seven centers in South America. Twinning programs between MISPHO centers and centers in high-income countries (HIC) have proven invaluable to harness the resources of these centers to improve pediatric oncology care in LIC. MISPHO educational efforts include oncology nursing, supportive care, cancer-specific updates, epidemiology, and clinical research methods. Educational efforts are facilitated by educational content and online conferencing via www.cure4kids.org. Identifying preventable causes of abandonment of therapy and documenting the nutritional status of patients treated at MISPHO centers are areas of active research.

Adolescent↗
PubMed2007

Impact of an education program on late diagnosis of retinoblastoma in Honduras.

BACKGROUND: In developed countries, more than 90% of children with retinoblastoma present with limited-stage disease and are cured; however, in countries with limited resources, like Honduras, most patients present with advanced disease and cure rates are less than 50%. Early diagnosis is necessary to improve the survival of children with retinoblastoma in these countries. PROCEDURE: We describe the preliminary results of a retinoblastoma education program linked to a national vaccination campaign in Honduras. Posters and flyers were designed to be accessible to poorly educated readers, to convey the severity of retinoblastoma, and to provide contact information. Charts and an electronic database were reviewed to determine age at diagnosis, presenting signs and symptoms, date of diagnosis, and outcome. RESULTS: During the eight previous years (July 1995-June 2003), 73% of the 59 diagnosed cases of retinoblastoma were extraocular; in contrast, during the post-campaign period (June 2003-January 2005), only 35% of the 23 diagnosed cases showed extraocular spread (P = 0.002). More than one-third of patients in both time periods either refused therapy or abandoned treatment. CONCLUSION: This inexpensive approach is an effective first step toward improving survival of childhood retinoblastoma. Abandonment and refusal of therapy are continuing obstacles.

Child↗
PubMed2006

Secondary chromosomal abnormalities predict outcome in pediatric and adult high-stage Burkitt lymphoma.

BACKGROUND: Karyotypic abnormalities in sporadic Burkitt lymphoma (BL) have been described extensively. However, to the authors' knowledge, very limited studies have focused on the secondary chromosomal abnormalities in pediatric BL as compared with those of adult BL and on their prognostic impact. METHODS: A retrospective analysis was performed in all pediatric and adult patients at 2 institutions, with a morphologic diagnosis of BL, pretherapy tumor karyotype available, and t(8;14), t(8;22), or t(2;8) present. RESULTS: There were 33 children and 37 adults. The majority of the patients (95%) had Stage III/IV disease. There were no statistically significant differences noted in karyotype complexity and the nature of the chromosomal abnormalities between these 2 groups. Abnormalities of chromosomes 13 (13q) and 22 (22q) had a negative impact on prognosis in children. In adults, abnormalities of chromosome 17 appeared to have a negative impact. CONCLUSIONS: The current findings suggest that karyotypic information can be used for refining risk stratification in patients with BL.

Adolescent↗
PubMed2006

Body mass index does not influence pharmacokinetics or outcome of treatment in children with acute lymphoblastic leukemia.

There is conflicting information about the influence of body mass index (BMI) on the pharmacokinetics, toxicity, and outcome of chemotherapy. We compared pharmacokinetics, outcome, and toxicity data across 4 BMI groups (underweight, BMI < or = 10th percentile; normal; at risk of overweight, BMI > or = 85th and < 95th percentile; overweight, BMI > or = 95th percentile) in 621 children with acute lymphoblastic leukemia (ALL) treated on 4 consecutive St Jude Total Therapy studies. Chemotherapy doses were not adjusted to ideal BMI. Estimates of overall survival (86.1% +/- 3.4%, 86.0% +/- 1.7%, 85.9% +/- 4.3%, and 78.2% +/- 5.5%, respectively; P = .533), event-free survival (76.2% +/- 4.2%, 78.7% +/- 2.1%, 73.4% +/- 5.5%, and 72.7% +/- 5.9%, respectively; P = .722), and cumulative incidence of relapse (16.0% +/- 3.7%, 14.4% +/- 1.8%, 20.6% +/- 5.1%, and 16.7% +/- 5.1%, respectively; P = .862) did not differ across the 4 groups. In addition, the intracellular levels of thioguanine nucleotides and methotrexate polyglutamates did not differ between the 4 BMI groups (P = .73 and P = .74, respectively). The 4 groups also did not differ in the overall incidence of grade 3 or 4 toxicity during the induction or postinduction periods. Further, the systemic clearance of methotrexate, teniposide, etoposide, and cytarabine did not differ with BMI (P > .3). We conclude that BMI does not affect the outcome or toxicity of chemotherapy in this patient population with ALL.

Adolescent↗
PubMed2006

Prognostic significance of CD20 expression in childhood B-cell precursor acute lymphoblastic leukemia.

CD20 expression is associated with inferior survival in adults with acute lymphoblastic leukemia (ALL). We analyzed the prognostic impact of CD20 expression in 353 children with B-cell precursor ALL treated in 3 consecutive St Jude Total Therapy studies. CD20 expression (> 20%) was found in 169 patients (48%) and was more frequent in patients between 1 and 10 years of age than in those younger than 1 or older than 10 years (P = .001). None of 14 patients with MLL-AF4 expressed CD20. There was no association between CD20 expression and E2A-PBX, TEL-AML1, ploidy, white blood cell count at diagnosis, or sex. In contrast to the experience in adult ALL, our patients with CD20 expression tended to have a better treatment outcome than those without the expression: 5-year event-free survival 84% +/- 2.9% versus 78% +/- 3.1% (P = .08). These data suggest that CD20 expression is not associated with inferior outcome in pediatric patients treated with contemporary regimens.

Age Factors↗
PubMed2006

Epigenetic regulation of human gamma-glutamyl hydrolase activity in acute lymphoblastic leukemia cells.

Gamma-glutamyl hydrolase (GGH) catalyzes degradation of the active polyglutamates of natural folates and the antifolate methotrexate (MTX). We found that GGH activity is directly related to GGH messenger RNA expression in acute lymphoblastic leukemia (ALL) cells of patients with a wild-type germline GGH genotype. We identified two CpG islands (CpG1 and CpG2) in the region extending from the GGH promoter through the first exon and into intron 1 and showed that methylation of both CpG islands in the GGH promoter (seen in leukemia cells from approximately 15% of patients with nonhyperdiploid B-lineage ALL) is associated with significantly reduced GGH mRNA expression and catalytic activity and with significantly higher accumulation of MTX polyglutamates (MTXPG(4-7)) in ALL cells. Furthermore, methylation of CpG1 was leukemia-cell specific and had a pronounced effect on GGH expression, whereas methylation of CpG2 was common in leukemia cells and normal leukocytes but did not significantly alter GGH expression. These findings indicate that GGH activity in human leukemia cells is regulated by epigenetic changes, in addition to previously recognized genetic polymorphisms and karyotypic abnormalities, which collectively determine interindividual differences in GGH activity and influence MTXPG accumulation in leukemia cells.

Adolescent↗
PubMed2006

Impact of age on outcome of pediatric acute myeloid leukemia: a report from 2 institutions.

BACKGROUND: The prognostic significance of age among pediatric patients with acute myeloid leukemia (AML) was investigated. METHODS: The authors reviewed the outcome of 424 patients who were <or=21 years of age at the time of diagnosis of AML (excluding acute promyelocytic leukemia) between 1983 and 2002 at St. Jude Children's Research Hospital (n=288) or the M. D. Anderson Cancer Center (n=136). Two treatment eras (1983-1989 and 1990-2002) were examined because of the greater intensity of treatment during the recent era. RESULTS: After controlling for the effects of cytogenetics, white blood cell (WBC) count, French-American-British (FAB) subtype, and treatment era, they observed that age and treatment era interacted significantly in relation to event-free survival (EFS) (P=.033). Patients 10 years of age or older were at greater risk of an adverse event than younger patients in the recent era (hazard ratio=1.8; 95% confidence interval [CI]: 1.3-2.6; P=.005) but not in the early era. The rate of adverse events (death or recurrence) increased significantly with each year of age in the recent era (4.3%/year; 95% CI: 1.9-6.8%; P=.001) but not in the early era. The rate of death increased significantly with each year of age in both eras (4.4%/year; 95% CI: 2.3-6.5%; P<.001). EFS and survival showed no association with study site, and the effects of age were similar at the 2 sites. CONCLUSIONS: These results suggest that age is an independent prognostic factor in childhood AML and that children younger than 10 years benefit more than older children from newer intensive therapies.

Acute Disease↗
PubMed2006

Rapid genotyping of common deficient thiopurine S-methyltransferase alleles using the DNA-microchip technique.

Thiopurine drugs are metabolized, in part, by S-methylation catalyzed by thiopurine S-methyltransferase (TPMT). Patients with very low or undetectable TPMT activity are at high risk of severe, potentially fatal hematopoietic toxicity when they are treated with standard doses of thiopurines. As human TPMT activity is controlled by a common genetic polymorphism, it is an excellent candidate for the clinical application of pharmacogenetics. Here, we report a new molecular approach developed to detect point mutations in the TPMT gene that cause the loss of TPMT activity. A fluorescently labeled amplified DNA is hybridized with oligonucleotide DNA probes immobilized in gel pads on a biochip. The specially designed TPMT biochip can recognize six point mutations in the TPMT gene and seven corresponding alleles associated with TPMT deficiency: TPMT*2; TPMT*3A, TPMT*3B, TPMT*3C, TPMT*3D, TPMT*7, and TPMT*8. The effectiveness of the protocol was tested by genotyping 58 samples of known genotype. The results showed 100% concordance between the biochip-based approach and the established PCR protocol. The genotyping procedure is fast, reliable and can be used for rapid screening of inactivating mutations in the TPMT gene. The study also provides the first data on the frequency of common TPMT variant alleles in the Russian population, based on a biochip analysis of 700 samples. TPMT gene mutations were identified in 44 subjects; genotype *1/*3A was most frequent.

Adolescent↗
PubMed2006

Identification of a novel germ line variant hotspot mutant p53-R175L in pediatric adrenal cortical carcinoma.

Hotspot mutations in the p53 tumor suppressor gene result in the disruption of DNA contact points or alter the overall structure of the protein to prevent DNA binding. When inherited, hotspot mutants are associated with Li-Fraumeni syndrome (LFS), a familial cancer predisposition. One of the most common hotspot mutations occurs at codon 175, resulting in an arginine to histidine substitution. We have identified a novel germ line variant of the 175 mutant (Arg to Leu; R175L) in a pediatric patient who developed adrenal cortical carcinoma. Surprisingly, the family is not tumor prone or associated with LFS. In vitro, the R175L mutant displayed an attenuated tumor suppressor activity in the regulation of transcription, colony formation, and apoptosis when compared with wild-type p53 and the R175H mutant. These findings suggest that p53-R175L retains sufficient activity to suppress LFS, but not adrenal cortical carcinoma. Therefore, not all hotspot mutants are functionally equivalent and the biochemical nature of the mutant may significantly influence clinical outcome. The implications of these results for genetic counseling are discussed.

Adrenal Cortex Neoplasms↗
PubMed2006

Use of [18F]fluorodeoxyglucose positron emission tomography in evaluating locally recurrent and metastatic adrenocortical carcinoma.

CONTEXT: Adrenocortical carcinomas are uncommon, and their evaluation by [(18)F]fluorodeoxyglucose positron emission tomography (FDG PET) has not been well evaluated. OBJECTIVE: The purpose of this study was to examine the potential utility of FDG PET in the detection of recurrent or metastatic adrenocortical carcinoma. DESIGN: In patients with known adrenocortical carcinoma who underwent FDG-PET imaging for suspected recurrence or metastasis, FDG activity was compared with other imaging findings, clinical features, and the presence or absence of disease as confirmed by resection, biopsy, or clinical follow-up. SETTING: The study took place at four tertiary referral centers. PATIENTS OR OTHER PARTICIPANTS: Twelve patients (10 females and two males, 5-71 yr of age) were evaluated. MAIN OUTCOME MEASURES: The main outcome measures were FDG activity, other imaging findings, and clinical features. RESULTS: Abnormal FDG uptake correctly indicated tumor recurrence in 10 patients. One patient with no abnormal FDG activity had a morphological abnormality subsequently proven to be a postoperative scar. Two patients, one with very small pulmonary lesions and one with a hepatic metastasis, had false-negative findings. CONCLUSIONS: Most adrenocortical carcinomas accumulate and retain FDG and thus can be visualized by PET. However, false-negative findings are possible, especially with very small lesions.

Adrenal Cortex Neoplasms↗
PubMed2006

SF-1 overexpression in childhood adrenocortical tumours.

The steroidogenic factor 1 (SF-1) gene encodes a transcription factor playing a pivotal role in the regulation of adrenogenital development. We have recently shown that SF-1 is amplified in childhood adrenocortical tumours (ACT). This study was aimed to assess if an increase in SF-1 gene copy number was associated with increased protein levels and to study the correlation between SF-1 expression and ACT clinical parameters. An increased SF-1 copy number was detected in eight of the 10 ACT cases studied. Conversely, the SF-1 protein was found to be overexpressed in all cases, compared to normal age-matched adrenal glands. No significant correlation was found between SF-1 protein levels and its gene copy number. Furthermore, no significant correlation existed with histological grade or with the clinical manifestation or evolution of disease. This data show that SF-1 overexpression is widespread in childhood ACT and is likely to play a role in its pathogenesis.

Adrenal Cortex Neoplasms↗
PubMed2006

A simplified flow cytometric assay identifies children with acute lymphoblastic leukemia who have a superior clinical outcome.

Bone marrow normal lymphoid progenitors (CD19+, CD10+, and/or CD34+) are exquisitely sensitive to corticosteroids and other antileukemic drugs. We hypothesized that, in patients with B-lineage acute lymphoblastic leukemia (ALL), cells with this phenotype detected early in treatment should be leukemic rather than normal. We therefore developed a simple and inexpensive flow cytometric assay for such cells and prospectively applied it to bone marrow samples collected on day 19 from 380 children with B-lineage ALL. In 211 patients (55.5%), these cells represented 0.01% or more of the mononuclear cells; results correlated remarkably well with those of more complex flow cytometric and molecular minimal residual disease (MRD) evaluations. Among 84 uniformly treated children, the 10-year incidence of relapse or remission failure was 28.8% +/- 7.1% (SE) for the 42 patients with 0.01% or more leukemic cells on day 19 detected by the simplified assay versus 4.8% +/- 3.3% for the 42 patients with lower levels (P = .003). These assay results were the strongest predictor of outcome, even after adjustment for competing clinicobiologic variables. Thus, this new assay would enable most treatment centers to identify a high proportion of children with ALL who have an excellent early treatment response and a high likelihood of cure.

Antigens, CD19↗