1,721,068 research outputs found
Meta-analysis of randomised adjuvant therapy trials for pancreatic cancer
No full textThe aim of this study was to investigate the worldwide evidence of the roles of adjuvant chemoradiation and adjuvant chemotherapy on survival in potentially curative resected pancreatic cancer. Five randomised controlled trials of adjuvant treatment in patients with histologically proven pancreatic ductal adenocarcinoma were identified, of which the four most recent trials provided individual patient data (875 patients). This meta-analysis includes previously unpublished follow-up data on 261 patients. The pooled estimate of the hazard ratio (HR) indicated a 25% significant reduction in the risk of death with chemotherapy (H = 0.75, 95% confidence interval (CI): 0.64, 0.90, P-values(stratified) (Pstrat) = 0.001) with median survival estimated at 19.0 (95% CI: 16.4, 21.1) months with chemotherapy and 13.5 (95% CI: 12.2, 15.8) without. The 2- and 5-year survival rates were estimated at 38 and 19%, respectively, with chemotherapy and 28 and 12% without. The pooled estimate of the HR indicated no significant difference in the risk of death with chemoradiation (HR = 1.09, 95% CI: 0.89, 1.32, Pstrat = 0.43) with median survivals estimated at 15.8 (95% CI: 13.9, 18.1) months with chemoradiation and 15.2 (95% CI: 13.1, 18.2) without. The 2- and 5-year survival rates were estimated at 30 and 12%, respectively, with chemoradiation and 34 and 17% without. Subgroup analyses estimated that chemoradiation was more effective and chemotherapy less effective in patients with positive resection margins. These results show that chemotherapy is effective adjuvant treatment in pancreatic cancer but not chemoradiation. Further studies with chemoradiation are warranted in patients with positive resection margins, as chemotherapy appeared relatively ineffective in this patient subgroup
Statistical Modelling for the Prognostic Classification of Patients with Pancreatic Cancer for Optimisation of Treatment Allocation [PhD Thesis]
Full text linkPancreatic cancer is a common cause of cancer death and is difficult to diagnose and treat. A prognostic index is a tool that can be used in clinical practice to predict survival. Thirty six prognostic factor studies were identified but the size and statistical methods were inappropriate. Valid statistical analyses are essential to make best use of data and optimise clinical application. Continuous variables are often simplified incorrectly by i) assuming linear relationships between predictors and log-hazard or ii) using dichotomisation. Non-linearity is addressed for the first time in this disease site using restricted cubic spline and fractional polynomial functions, ideal for smooth curved relationships. Multivariable models containing non-linear transformations gave a substantially better fit. Important effects of some covariates were unrecognised under simplistic assumptions. The fitted functions generated by the two methods were similar. A direct comparison of these strategies was based on a novel approach assessing the difference in the AIC values by calculating a sampling distribution in multiple bootstrap resamples. Model validation is also addressed for the first time in this disease and suggested minimal over-fitting with reproducible prognostic information when fitted to external data. This thesis provides the first validated prognostic tool in advanced pancreatic cancer developed using appropriate statistical methodology. Four risk-sets identified by the model could help clinicians target treatments to patients more appropriately and have an impact on future trial design and analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Influence of Surgical Resection and Post-Operative Complications on Survival following Adjuvant Treatment for Pancreatic Cancer in the ESPAC-1 Randomized Controlled Trial
No full textThe influence of type of surgery and occurrence of post-operative complications on survival following adjuvant therapy for pancreatic cancer are uncertain. Methods: Cox proportional hazard modelling was used to investigate the influence of type of surgery and the presence of complications on survival in conjunction with clinico-pathological variables in the 550 patients of the ESPAC-1 adjuvant randomized controlled trial. Results: Standard Kausch-Whipple (KW) was performed in 282 (54%) patients, 186 (35%) had a pylorus-preserving (PP) KW, 39 (7%) had a distal pancreatectomy and 21 (4%) had a total pancreatectomy. Post-operative complications were reported in 140 (27%) patients. PP-KW patients survived longer with a median (95% CI) survival of 19.9 (17.3, 23.1) months compared to 14.8 (13.0, 16.7) for KW patients (χ2LR = 15.1, p < 0.001). KW patients were more likely however to have R1 margins (67 (24%) vs. 29 (16%), χ2 = 4.59, p = 0.032), poorly differentiated tumours (70 (26%) vs. 19 (10%), χ2 = 18.65, p < 0.001) and positive lymph nodes (165 (60%) vs. 81 (44%), χ2 = 11.32, p < 0.001). Post-operative complications did not significantly affect survival. Independent prognostic factors were tumour grade, nodal status and tumour size but not type of surgery or post-operative complications. There was a survival benefit for chemotherapy irrespective of the type of surgery or post-operative complications. Conclusions: The KW and PP-KW procedures did not significantly influence the hazard of death in the presence of tumour staging, demonstrating that ESPAC-1 surgeons showed good judgement in their choice of operation. Post-operative complications did not adversely affect the survival benefit from adjuvant chemotherapy
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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