Tomasz Burzykowski

Summary

Affiliation: Hasselt University
Country: Belgium

Publications

  1. doi The correlation structure of longitudinal measurements of vision in patients with macular degeneration
    Tomasz Burzykowski
    International Drug Development Institute IDDI, Louvain la Neuve, Belgium Interuniversity Institute for Biostatistics and Statistical Bioinformatics I BioStat, Hasselt University, Diepenbeek, Belgium
    Pharm Stat 10:115-21. 2011
  2. ncbi Surrogate threshold effect: an alternative measure for meta-analytic surrogate endpoint validation
    Tomasz Burzykowski
    Center for Statistics, Hasselt University, Agoralaan bldg D, B3590 Diepenbeek, Belgium
    Pharm Stat 5:173-86. 2006
  3. doi Evaluation of tumor response, disease control, progression-free survival, and time to progression as potential surrogate end points in metastatic breast cancer
    Tomasz Burzykowski
    Hasselt University, Center for Statistics, Agoralaan, Bldg D, 3590 Diepenbeek, Belgium
    J Clin Oncol 26:1987-92. 2008
  4. doi Exploring and validating surrogate endpoints in colorectal cancer
    Tomasz Burzykowski
    Center for Statistics, Hasselt University, Agoralaan D, 3590 Diepenbeek, Belgium
    Lifetime Data Anal 14:54-64. 2008
  5. ncbi A modeling approach to the analysis of nerve regenerative experiments
    Suzy van Sanden
    Center for Statistics, Hasselt University, Center for Statistics, Diepenbeek, Belgium
    J Biopharm Stat 16:843-59. 2006
  6. doi Fitting conditional survival models to meta-analytic data by using a transformation toward mixed-effects models
    Goele Massonnet
    Hasselt University, Center for Statistics, Agoralaan, Building D, B 3590 Diepenbeek, Belgium
    Biometrics 64:834-42. 2008
  7. doi A unified framework for the evaluation of surrogate endpoints in mental-health clinical trials
    Geert Molenberghs
    I Biostat, Hasselt University, Diepenbeek, Belgium
    Stat Methods Med Res 19:205-36. 2010
  8. ncbi Using linear mixed models for normalization of cDNA microarrays
    Philippe Haldermans
    Hasselt University, Belgium
    Stat Appl Genet Mol Biol 6:Article 19. 2007
  9. ncbi Prentice's approach and the meta-analytic paradigm: a reflection on the role of statistics in the evaluation of surrogate endpoints
    Ariel Alonso
    Center for Statistics, Limburgs Universitair Centrum, Diepenbeek, Belgium
    Biometrics 60:724-8. 2004
  10. doi Individual- and trial-level surrogacy in colorectal cancer
    Marc Buyse
    IDDI International Drug Development Institute, Louvain la Neuve, Belgium and Center for Statistics, Hasselt University, Diepenbeek, Belgium
    Stat Methods Med Res 17:467-75. 2008

Collaborators

Detail Information

Publications49

  1. doi The correlation structure of longitudinal measurements of vision in patients with macular degeneration
    Tomasz Burzykowski
    International Drug Development Institute IDDI, Louvain la Neuve, Belgium Interuniversity Institute for Biostatistics and Statistical Bioinformatics I BioStat, Hasselt University, Diepenbeek, Belgium
    Pharm Stat 10:115-21. 2011
    ..In this paper we investigate, by using data from two randomized clinical trials, the mean and variance-covariance structures of the longitudinal measurements of the change in visual acuity...
  2. ncbi Surrogate threshold effect: an alternative measure for meta-analytic surrogate endpoint validation
    Tomasz Burzykowski
    Center for Statistics, Hasselt University, Agoralaan bldg D, B3590 Diepenbeek, Belgium
    Pharm Stat 5:173-86. 2006
    ..One of its interesting features, apart from providing information relevant to the practical use of a surrogate endpoint, is its natural interpretation from a clinical point of view...
  3. doi Evaluation of tumor response, disease control, progression-free survival, and time to progression as potential surrogate end points in metastatic breast cancer
    Tomasz Burzykowski
    Hasselt University, Center for Statistics, Agoralaan, Bldg D, 3590 Diepenbeek, Belgium
    J Clin Oncol 26:1987-92. 2008
    ....
  4. doi Exploring and validating surrogate endpoints in colorectal cancer
    Tomasz Burzykowski
    Center for Statistics, Hasselt University, Agoralaan D, 3590 Diepenbeek, Belgium
    Lifetime Data Anal 14:54-64. 2008
    ..J Clin Oncol 22:484-492, 2004). Our analysis supports the conclusion of Sargent et al. and shows that using DFS at 2 or 3 years would be the best option for the prediction of OS at 5 years...
  5. ncbi A modeling approach to the analysis of nerve regenerative experiments
    Suzy van Sanden
    Center for Statistics, Hasselt University, Center for Statistics, Diepenbeek, Belgium
    J Biopharm Stat 16:843-59. 2006
    ..The benefits of the model as well as problems that can occur are illustrated and discussed...
  6. doi Fitting conditional survival models to meta-analytic data by using a transformation toward mixed-effects models
    Goele Massonnet
    Hasselt University, Center for Statistics, Agoralaan, Building D, B 3590 Diepenbeek, Belgium
    Biometrics 64:834-42. 2008
    ..The proposed method is applied to data from 27 randomized trials in advanced colorectal cancer, which are available through the Meta-Analysis Group in Cancer...
  7. doi A unified framework for the evaluation of surrogate endpoints in mental-health clinical trials
    Geert Molenberghs
    I Biostat, Hasselt University, Diepenbeek, Belgium
    Stat Methods Med Res 19:205-36. 2010
    ..Implications for design and for predicting the effect of treatment in a new trial, based on the surrogate, are discussed. A case study in schizophrenia is analysed...
  8. ncbi Using linear mixed models for normalization of cDNA microarrays
    Philippe Haldermans
    Hasselt University, Belgium
    Stat Appl Genet Mol Biol 6:Article 19. 2007
    ..A second dataset, coming from the apo AI experiment, was used to further illustrate the methods. Finally, a simulation study was done to compare between methods...
  9. ncbi Prentice's approach and the meta-analytic paradigm: a reflection on the role of statistics in the evaluation of surrogate endpoints
    Ariel Alonso
    Center for Statistics, Limburgs Universitair Centrum, Diepenbeek, Belgium
    Biometrics 60:724-8. 2004
    ..We briefly present a hierarchical framework that incorporates ideas from Prentice's work and is uniformly applicable to different types of surrogate and true clinical outcomes...
  10. doi Individual- and trial-level surrogacy in colorectal cancer
    Marc Buyse
    IDDI International Drug Development Institute, Louvain la Neuve, Belgium and Center for Statistics, Hasselt University, Diepenbeek, Belgium
    Stat Methods Med Res 17:467-75. 2008
    ..86. One trial with a large treatment effect on PFS and OS had a strong influence on the results in advanced disease. DFS (and PFS in advanced disease) are acceptable surrogates for OS in colorectal cancer...
  11. ncbi A version of the EM algorithm for proportional hazard model with random effects
    Jose Cortinas Abrahantes
    Center for Statistics, Limburgs Universitair Centrum, Universitaire Campus, B 3590 Diepenbeek, Belgium
    Biom J 47:847-62. 2005
    ..The method is computationally less demanding than the approaches developed previously. Its performance is assessed based on a simulation study and compared to a non-EM based estimation approach proposed by Ripatti and Palmgren (2000)...
  12. doi An efficient method to calculate the aggregated isotopic distribution and exact center-masses
    Jürgen Claesen
    I Biostat, Hasselt University, Diepenbeek, Belgium
    J Am Soc Mass Spectrom 23:753-63. 2012
    ..The algorithm will be made available as a Bioconductor package in R, and is also available upon request...
  13. doi A cross-validation study to select a classification procedure for clinical diagnosis based on proteomic mass spectrometry
    Dirk Valkenborg
    Hasselt University, Center for Statistics
    Stat Appl Genet Mol Biol 7:Article12. 2008
    ..For the training data set, the total error rate for the classification rule, as estimated by using leave-one-out cross-validation, was equal to 0.16, with the sensitivity and specificity equal to 0.87 and 0.82, respectively...
  14. doi Markov-chain-based heteroscedastic regression model for the analysis of high-resolution enzymatically 18O-labeled mass spectra
    Qi Zhu
    I Biostat, Hasselt University, Diepenbeek, Belgium and VITO, Mol, Belgium
    J Proteome Res 9:2669-77. 2010
    ....
  15. ncbi Testing for trends in dose-response microarray experiments: a comparison of several testing procedures, multiplicity and resampling-based inference
    Dan Lin
    Hasselt University
    Stat Appl Genet Mol Biol 6:Article26. 2007
    ..Results on the number of significant genes from each statistic are discussed. A simulation study is conducted to investigate the power of each statistic. A R library IsoGene implementing the methods is available from the first author...
  16. doi A model-based method for the prediction of the isotopic distribution of peptides
    Dirk Valkenborg
    Center for Statistics, Hasselt University, Diepenbeek, Belgium
    J Am Soc Mass Spectrom 19:703-12. 2008
    ..Further, we extend our method to estimate the isotopic distribution of sulphur-containing peptides. This is important because the naturally occurring isotopes of sulphur have an impact on the isotopic distribution of a peptide...
  17. ncbi Design and analysis of drug combination experiments
    Roel Straetemans
    Limburgs Universitair Centrum, Center for Statistics, Biostatistics, Universitaire Campus, B 3590 Diepenbeek, Belgium
    Biom J 47:299-308. 2005
    ..The approach is illustrated using data coming from an oncology study in which the inhibition effect of a combination of two compounds is studied using 96-well plates and a fixed-ratio design...
  18. ncbi Pseudo-likelihood estimation for a marginal multivariate survival model
    Fabian Tibaldi
    Center for Statistics, Limburgs Universitair Centrum, Transnationale Universiteit Limburg, Diepenbeek Universitaire Campus, B3590 Diepenbeek, Belgium
    Stat Med 23:947-63. 2004
    ..The second study is on adoption data where the association of the survival times within families is modelled, illustrating the use of the proposed methodology for the context of population genetics...
  19. doi The use of the isotopic distribution as a complementary quality metric to assess tandem mass spectra results
    Fatemeh Zamanzad Ghavidel
    Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Belgium
    J Proteomics 98:150-8. 2014
    ..These results demonstrate that Pearson's χ(2) statistic can be used in conjunction with the score of database-search algorithms to increase the sensitivity and specificity of peptide identification...
  20. doi Comparison of the Mahalanobis distance and Pearson's χ² statistic as measures of similarity of isotope patterns
    Fatemeh Zamanzad Ghavidel
    I Biostat, Hasselt University, Hasselt, Belgium
    J Am Soc Mass Spectrom 25:293-6. 2014
    ..The results indicate that Pearson's χ(2) statistic has better discriminatory performance than the Mahalanobis distance and is a more robust measure. ..
  21. pmc Simultaneous mapping of multiple gene loci with pooled segregants
    Jürgen Claesen
    I Biostat, Hasselt University, Diepenbeek, Belgium
    PLoS ONE 8:e55133. 2013
    ..We exploit the link between smoothing splines and generalized mixed models for estimating the underlying structure present in the SNP scatterplots...
  22. pmc Predicting treatment effect from surrogate endpoints and historical trials: an extrapolation involving probabilities of a binary outcome or survival to a specific time
    Stuart G Baker
    National Cancer Institute, EPN 3131, Bethesda, Maryland 20892 7354, USA
    Biometrics 68:248-57. 2012
    ..To summarize the additional uncertainty from using a predicted instead of true result for the estimated treatment effect, we compute its multiplier of standard error. Software is available for download...
  23. pmc Individual patient data meta-analysis of randomized trials evaluating IL-2 monotherapy as remission maintenance therapy in acute myeloid leukemia
    Marc Buyse
    International Drug Development Institute, Louvain la Neuve, Belgium
    Blood 117:7007-13. 2011
    ..We conclude that IL-2 alone is not an effective remission maintenance therapy for AML patients in CR1...
  24. ncbi Progression-free survival is a surrogate for survival in advanced colorectal cancer
    Marc Buyse
    International Drug Development Institute, Louvain la Neuve, Belgium
    J Clin Oncol 25:5218-24. 2007
    ..We investigated whether progression-free survival (PFS) could be considered a valid surrogate for OS in advanced colorectal cancer...
  25. pmc Evaluation of normalization methods to pave the way towards large-scale LC-MS-based metabolomics profiling experiments
    Bedilu Alamirie Ejigu
    I Biostat, Hasselt University, Diepenbeek, Belgium
    OMICS 17:473-85. 2013
    ..Moreover, data-driven normalization methods are the best option to normalize datasets from untargeted LC-MS experiments...
  26. doi A statistical approach to central monitoring of data quality in clinical trials
    David Venet
    International Drug Development Institute, Louvain la Neuve, Belgium
    Clin Trials 9:705-13. 2012
    ..These activities are associated with high cost and a limited contribution to data quality. Central statistical monitoring is of particular interest to address these shortcomings...
  27. ncbi A perspective on surrogate endpoints in controlled clinical trials
    Geert Molenberghs
    Center for Statistics, Limburgs Universitair Centrum, Diepenbeek, Belgium
    Stat Methods Med Res 13:177-206. 2004
    ..Clearly statistical evidence should only be seen as a component in a decision making process that also involves a number of clinical and biological considerations...
  28. doi The isotopic distribution conundrum
    Dirk Valkenborg
    Flemish Institute for Technological Research, VITO, Mol, Belgium
    Mass Spectrom Rev 31:96-109. 2012
    ..2008] J Am Soc Mass Spectrom, 19:1867-1874). We also comment on the ideas to use Punnet squares and Pascal's triangle to introduce the concept of the isotopic distribution for educational and didactic purposes...
  29. ncbi Predicted and observed thyroid cancer incidence in Poland after year 1986
    Tomasz Burzykowski
    Center for Statistics, Limburgs Universitair Centrum, Diepenbeek, Belgium
    Wiad Lek 57:306-10. 2004
    ..For males, however, an alternative possibility of a linear increase of incidence rates might also be applicable. To reach a more definite conclusion in this case, further follow up is needed...
  30. ncbi Using a Poisson approximation to predict the isotopic distribution of sulphur-containing peptides in a peptide-centric proteomic approach
    Dirk Valkenborg
    Center for Statistics, Hasselt University, Agoralaan D, 3590 Diepenbeek, Belgium
    Rapid Commun Mass Spectrom 21:3387-91. 2007
    ..The results are not simply restricted to a COFRADIC setting but are also applicable more generally, for any method which enriches for sulphur-containing peptides...
  31. ncbi The use of background signal in the transformation of cDNA-microarray measurements
    Suzy van Sanden
    Center for Statistics, Hasselt University, Agoralaan, Diepenbeek, Belgium
    Appl Bioinformatics 5:161-72. 2006
    ..Overall, the best results are obtained with our proposed transformation that takes the background measurements into account...
  32. ncbi Statistical challenges in the evaluation of surrogate endpoints in randomized trials
    Geert Molenberghs
    Limburgs Universitair Centrum, TUL, Center for Statistics, Biostatistics, Diepenbeek, Belgium
    Control Clin Trials 23:607-25. 2002
    ..In this paper, we argue that such a multiunit approach should be adopted because it overcomes difficulties that necessarily surround validation efforts based on a single trial. These difficulties are highlighted...
  33. ncbi Is there a minimum number of lymph nodes that should be histologically assessed for a reliable nodal staging of T3N0M0 colorectal carcinomas?
    Gabor Cserni
    Department of Pathology, Bács Kiskun County Hospital, Kecskemet, Hungary
    J Surg Oncol 81:63-9. 2002
    ..Because of the existing controversy, we searched for a cutoff value for the number of lymph nodes (LNs) to be examined in order to establish a reliable node-negative stage in colorectal carcinomas (CRCs)...
  34. ncbi Functional form of the effect of the numbers of axillary nodes on survival in early breast cancer
    Vincent Vinh-Hung
    Department of Radiotherapy, Oncologisch Centrum, AZ VUB, B 1090 Jette, Belgium
    Int J Oncol 22:697-704. 2003
    ..Even when the number of involved nodes is already large, each additional involved node increases the relative mortality hazard by at least 1.3%...
  35. doi Taxanes alone or in combination with anthracyclines as first-line therapy of patients with metastatic breast cancer
    Martine J Piccart-Gebhart
    Institut Jules Bordet, 121 Boulevard de Waterloo, 1000 Brussels, Belgium
    J Clin Oncol 26:1980-6. 2008
    ..This meta-analysis uses data from all relevant trials to detect any advantages of taxanes in terms of tumor response, progression-free survival (PFS), and survival...
  36. ncbi Using the expected survival to explain differences between the results of randomized trials: a case in advanced ovarian cancer
    Marc Buyse
    ScD, International Drug Development Institute Inc, American Twine Office Park, 222 Third St, Suite 0342, Cambridge, MA 02142, USA
    J Clin Oncol 21:1682-7. 2003
    ..98). In this article, we show how these discrepant results can be reconciled through the estimation of expected survival curves...
  37. ncbi Reintroduction of oxaliplatin is associated with improved survival in advanced colorectal cancer
    Aimery de Gramont
    Hopital Saint Antoine, Paris Cedex 12, France
    J Clin Oncol 25:3224-9. 2007
    ....
  38. ncbi Statistical interaction in the survival analysis of early breast cancer using registry data: role of breast conserving surgery and radiotherapy
    Vincent Vinh-Hung
    Oncology Center, Academic Hospital, Vrije Universiteit Brussels, Jette, Belgium
    Tumori 91:9-14. 2005
    ..To identify subgroup effects that might influence the survival results of postoperative radiotherapy...
  39. ncbi Are prostate-specific antigen changes valid surrogates for survival in hormone-refractory prostate cancer? A meta-analysis is needed!
    Laurence Collette
    J Clin Oncol 25:5673-4; author reply 5674. 2007
  40. ncbi Vegetables affect the expression of genes involved in carcinogenic and anticarcinogenic processes in the lungs of female C57BL/6 mice
    Simone G van Breda
    Department of Health Risk Analysis and Toxicology, Maastricht University, Maastricht, The Netherlands
    J Nutr 135:2546-52. 2005
    ..The current study provides more insight into the genetic mechanisms by which vegetables, in particular carrots, can prevent lung cancer risk...
  41. ncbi Is prostate-specific antigen a valid surrogate end point for survival in hormonally treated patients with metastatic prostate cancer? Joint research of the European Organisation for Research and Treatment of Cancer, the Limburgs Universitair Centrum, and
    Laurence Collette
    European Organization for Research and Treatment of Cancer Data Center, Avenue Emmanuel Mounier 83 11, B 1200 Brussels, Belgium
    J Clin Oncol 23:6139-48. 2005
    ..It could be shortened by using surrogate end points. Prostate-specific antigen (PSA) is the most studied biomarker in prostate cancer (PCa). This study attempts to validate PSA end points as surrogates for OS in advanced PCa...
  42. ncbi Vegetables affect the expression of genes involved in anticarcinogenic processes in the colonic mucosa of C57BL/6 female mice
    Simone G J van Breda
    Department of Health Risk Analysis and Toxicology, Maastricht University, The Netherlands
    J Nutr 135:1879-88. 2005
    ..These genes are of particular interest because they were consistently affected and could be involved in the prevention of CRC by vegetable consumption...
  43. ncbi Multivariate analysis of risk factors for development of duodenal ulcer in Helicobacter pylori-infected patients
    Jaroslaw Regula
    Department of Gastroenterology, Medical Center for Postgraduate Education, Warsaw, Poland
    Digestion 67:25-31. 2003
    ..Although Helicobacter pylori is a significant etiologic factor of peptic ulcer disease, it remains unknown why ulcers develop only in the minority of infected individuals...
  44. ncbi Titrating Theileria parva: single stocks against combination of stocks
    Niko Speybroeck
    Institute of Tropical Medicine, Animal Health, Nationalestraat, Antwerp, Belgium
    Exp Parasitol 118:522-30. 2008
    ..parva have not yielded the results that might be expected of them. The results of this work may also have implications for the use of antigen cocktails in cancer, HIV and malaria vaccine trials...
  45. ncbi Post-surgery radiation in early breast cancer: survival analysis of registry data
    Vincent Vinh-Hung
    Oncologisch Centrum, AZ VUB, 101 Laarbeeklaan, B 1090 Jette, Belgium
    Radiother Oncol 64:281-90. 2002
    ..Overviews of randomized trials have shown a small survival advantage with post-surgery radiation in early breast cancer. The present study attempts to extend this observation through a systematic analysis of population data. Materials and..
  46. ncbi Axillary sentinel node and tumour-related factors associated with non-sentinel node involvement in breast cancer
    Gabor Cserni
    Bacs Kiskun County Teaching Hospital, Medical School of the University of Sciences at Szeged, H 6000 Kecskemet, Hungary
    Jpn J Clin Oncol 34:519-24. 2004
    ..These patients are exposed to the morbidity of axillary clearance without any expected therapeutic benefit...
  47. ncbi Effect of the number of uninvolved nodes on survival in early breast cancer
    Vincent Vinh-Hung
    Department of Radiotherapy, Oncologisch Centrum, AZ VUB, B 1090 Jette, Belgium
    Oncol Rep 10:363-8. 2003
    ..The incidental finding that ratio-based characterization of node involvement might be a prognostic factor will be further investigated...
  48. ncbi Efficacy of oral adjuvant therapy after resection of colorectal cancer: 5-year results from three randomized trials
    Junichi Sakamoto
    Department of Epidemiological and Clinical Research Information Management, Graduate School of Medicine, Kyoto University, Yoshidakonoe cho, Sakyo ku, Kyoto 606 8501, Japan
    J Clin Oncol 22:484-92. 2004
    ..The purpose of this meta-analysis is to assess the survival and disease-free survival benefits of treating patients after surgical resection of a primary colorectal tumor with oral fluoropyrimidines for 1 year...
  49. ncbi Prostate-specific antigen (PSA) alone is not an appropriate surrogate marker of long-term therapeutic benefit in prostate cancer trials
    Laurence Collette
    European Organisation for Research and Treatment of Cancer EORTC Data Center, Avenue E Mounier 83 11, 1200 Brusells, Biostatistics Department, Brussels, Belgium
    Eur J Cancer 42:1344-50. 2006
    ..We give some recommendations for the planning of trials that would use PSA endpoints (in hormone refractory disease) and for the early stop of (endocrine treatment) trials on the basis of intermediate results based on PSA...