Tomasz Burzykowski

..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...

..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...

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..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...

..The benefits of the model as well as problems that can occur are illustrated and discussed...

..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...

..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...

..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...

..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...

..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...

..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)...

..The algorithm will be made available as a Bioconductor package in R, and is also available upon request...

..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...

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..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...

..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...

..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...

..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...

..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...

..We investigated whether progression-free survival (PFS) could be considered a valid surrogate for OS in advanced colorectal cancer...

..We conclude that IL-2 alone is not an effective remission maintenance therapy for AML patients in CR1...

..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...

..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...

..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...

..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...

..Overall, the best results are obtained with our proposed transformation that takes the background measurements into account...

..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...

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..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...

..To identify subgroup effects that might influence the survival results of postoperative radiotherapy...

..98). In this article, we show how these discrepant results can be reconciled through the estimation of expected survival curves...

..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)...

..Even when the number of involved nodes is already large, each additional involved node increases the relative mortality hazard by at least 1.3%...

..The incidental finding that ratio-based characterization of node involvement might be a prognostic factor will be further investigated...

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..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...

..These genes are of particular interest because they were consistently affected and could be involved in the prevention of CRC by vegetable consumption...

..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...

..The current study provides more insight into the genetic mechanisms by which vegetables, in particular carrots, can prevent lung cancer risk...

..Likewise, survival advantage was observed with post-surgery radiation and breast-conserving procedure in node negative patients...

..These patients are exposed to the morbidity of axillary clearance without any expected therapeutic benefit...

..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...

..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...