1,720,959 research outputs found
Risk of second brain tumor after conservative surgery and radiotherapy for pituitary adenoma: Update after an additional 10 years
No full textWe assessed the risk of second brain tumors in a cohort of patients with pituitary adenoma treated with conservative surgery and external beam radiotherapy. Four hundred and twenty-six patients (United Kingdom residents) with pituitary adenomas received radiotherapy at the Royal Marsden Hospital (RMH) between 1982 and 1994. They were followed up for 5749 person-years. The cumulative incidence of second intracranial tumors and systemic malignancy was compared with population incidence rates through the Thames Cancer Registry and the National Health Service Central Register (previously OPCS) to record death and the potential causes. Eleven patients developed a second brain tumor, including five meningiomas, four high grade astrocytomas, one meningeal sarcoma, and one primitive neuroectodermal tumor. The cumulative risk of second brain tumors was 2.0% [95% confidence interval (CI), 0.9-4.4%] at 10 yr and 2.4% (95% CI, 1.2-5.0%) at 20 yr, measured from the date of radiotherapy. The relative risk of second brain tumor compared with the incidence in the normal population was 10.5 (95% CI, 4.3-16.7). The relative risk was 7.0 for neuroepithelial and 24.3 for meningeal tumors. The relative risks were 24.2 (95% CI, 4.8-43.5), 2.9 (95% CI, 0-8.5), and 28.6 (95% CI, 0.6-56.6) during the intervals 5-9, 10-19, and more than 20 yr after radiotherapy (four cases occurred >20 yr after treatment). There was no evidence of excess risk of second systemic malignancy. An additional 10-yr update confirmed our previous report of an increased risk of second brain tumors in patients with pituitary adenoma treated with surgery and radiotherapy. The 2.4% risk at 20 yr remains low and should not preclude the use of radiotherapy as an effective treatment option. However, an increased risk of second brain tumors continues beyond 20 and 30 yr after treatment
Fractionated stereotactic radiotherapy in patients with skull base benign tumours: The Royal Marsden Hospital experience
No full textBACKGROUND: Stereotactic radiotherapy techniques have been recently employed in the control of skull base tumours as pituitary adenomas, craniopharyngiomas and meningiomas. OBJECTIVE: to assess the long-term outcome of fractionated stereotactic conformal radiotherapy in patients with residual and recurrent pituitary adenoma treated at Royal Marsden Hospital. PATIENTS AND METHODS: 245 patients with pituitary adenoma (n = 98), meningioma (n = 108) and craniopharyngioma (n = 39) were treated with fractionated stereotactic radiotherapy between 1995 and 2004. Patients were treated with 4-6 non-coplanar conformal fixed fields. Treatment was delivered in 25-33 daily fractions to a dose of 45-55 Gy. Results: the 5-year progression free survival was 98%, 92%, and 90% for pituitary adenoma, meningioma and craniopharyngioma. The respective 5-year survival was 98%, 97% and 100%. Ten patients required further debulking surgery for progressive disease (3 pituitary adenomas, 5 meningiomas and 2 craniopharyngiomas). The treatment was well tolerated with acceptable long-term toxicity. 15% of patients had a clinical improvement in neurological deficits following stereotactic radiotherapy. Hypopituitarism was the most common long-term effect and 33% of patients worsened pituitary function. Three patients had visual deterioration following stereotactic radiotherapy. CONCLUSION: Our results suggest that fractionated stereotactic radiotherapy is a high precise technique suitable for the treatment of skull base tumours with low toxicity. Tumour and hormone control are equivalent to those seen following conventional RT. Longer follow up is needed to assess a potential reduction in long-term morbidity. Copyright © 2007 by new Magazine edizioni s.r.l
Fractionated stereotactic conformal radiotherapy for secreting and nonsecreting pituitary adenomas
No full textObjective: To assess the medium-term outcome in a cohort of patients with residual or recurrent pituitary adenoma treated with fractionated stereotactic conformal radiotherapy (SCRT). Patients and methods: Ninety-two patients (median age 50 years) with a residual or recurrent nonfunctioning (67) or a secreting (25) pituitary adenoma were treated between 1995 and 2003. Eighteen patients had a GH-secreting, five PRL-secreting and two an ACTH-secreting pituitary adenoma. Vision was impaired in 39 patients, with visual field deficit (35) and/or reduced visual acuity (25). Sixty-four patients had partial or complete hypopituitarism before SCRT. The treatment was delivered stereotactically by four noncoplanar conformal fixed fields using a 6-MV linear accelerator to a dose of 45 Gy in 25 fractions. Results: At a median follow-up of 32 months (range 4-108) the 1, 3 and 5 years actuarial progression-free survival is 99%, 98% and 98%, and overall survival is 98%. Three patients recurred 5 months, 1 year and 9 years after SCRT requiring surgery. In secreting adenomas, hormone levels declined progressively, becoming normal in more than a third of patients with GH-secreting and PRL-secreting pituitary tumours. 50% of baseline GH level was achieved in just under 2 years. The treatment was well tolerated with minimal acute toxicity. Hypopituitarism was the most common long-term effect; 22% of patients had worsening of pituitary function. One patient developed unilateral quadrantopia without tumour progression. Conclusion: SCRT as a high-precision technique of localized irradiation achieves tumour and hormone control of pituitary adenomas comparable with previously published data on the efficacy of conventional radiotherapy. Despite the potential advantage of reducing the volume of normal brain irradiated, the theoretical benefit over conventional radiotherapy in terms of the reduction in long-term morbidity has not yet been demonstrated and requires longer follow-up. Potential effect on long-term cognitive function has not been tested. © 2006 Blackwell Publishing Ltd
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
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
- …
