1,721,357 research outputs found
Veranderingen in de TNM-classificatie van het hoofd-halscarcinoom
No full textThe TNM-classification of the UICC is used for staging malignant tumours worldwide. From 2003 the new revised sixth edition must be used. In comparison with the fifth edition there are some general and some head and neck carcinoma specific alterations. Some designations are introduced if sentinel lymph node procedure or immunohistochemistry or molecular methods have been used. In the revised version some definitions for advanced tumour stages at several head and neck sites are changed. In the new classification of the primary tumour the terms erosion and invasion of cartilage or bone are used. At most head and neck sites T4 is divided in T4a and T4b
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
Move to Eat: Towards personalization of supportive care for patients with head and neck cancer undergoing chemoradiotherapy
Full text linkThe diagnosis and treatment of head and neck cancer (HNC)significantly impact patients' lives. Tumor-related symptoms and toxicity of chemoradiotherapy (CRT) treatment often reduce oral food intake, leading to unintended weight loss, reduced muscle mass, and, malnutrition. Malnutrition negatively affects physical condition, treatment toxicity, complications, quality of life, healthcare costs, and survival. Dietary treatment aims to prevent or treat malnutrition early and optimize nutritional intake based on individual needs. When oral intake is insufficient, enteral nutrition via a nasogastric tube or gastrostomy is often required during CRT. Besides adequate nutritional intake is exercise a prerequisite for preventing muscle mass loss. Exercise programs in other cancer populations show benefits in fitness, fatigue, and treatment completion rates but has not been studied in the HNC population. A survey among 13 Dutch head and neck oncology centers revealed significant variation in dietetic care for head and neck cancer patients during CRT. The number of dietetic consultations ranged from two to seven during treatment. Also gastrostomy placement policy varied, with some centers placing them prophylactically in all patients (15%), prophylactically upon indication (39%), reactively (15%), or both (31%). Only 46% had protocols for placement. Standardized guidelines are recommended to optimize nutritional care. A predictive model for identifying patients needing prophylactic gastrostomy was developed using data from 450 HNC patients treated with CRT in two Dutch head and neck oncology centers. Key predictors for the use of tube feeding for at least four weeks included BMI, weight change, adjusted diet, weight change, performance status, tumor location, TNM classification, type of systemic treatment, and radiation doses to salivary glands. The model showed good discriminative value after internal validation (AUC 72.3%) and supports personalized decision-making but requires external validation. An updated model incorporating new predictors, such as radiation doses to swallowing muscles, was externally validated with data from four Dutch head and neck oncology centers (n=743). The final model includes pretreatment weight change, texture modified diet at baseline, ECOG performance status, tumor site, N classification, mean radiation dose to the contralateral parotid gland and oral cavity. The model demonstrated good accuracy (AUC 73%, 62% after validation). Prophylactic gastrostomy is recommended at a predicted risk of >90% and may be discussed at >70%. The feasibility of a 10-week tailored endurance and resistance training program during CRT was evaluated, quantitative and qualitative, in 40 HNC patients. Adherence (54%) and recruitment (36%) exceeded targets, based on studies in other cancer populations, but retention (65%) fell short, primarily due to treatment toxicity. Facilitators included physical/emotional benefits and home-based settings. A more personalized approach is needed to improve adherence and outcomes. Key findings highlight the need for personalized and integrated nutritional and exercise care pathways. The implementation of a gastrostomy decision model aligns with national healthcare priorities. Future research should focus on the long-term effects of combined nutrition and exercise interventions on quality of life, physical function, and clinical outcomes
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
Imaging of Head and Neck Cancer Patients Before, During and After Radiotherapy
No full textThis thesis shows that before, during and after radiotherapy medical imaging can aid the treatment of HNSCC patients. This appears to be particularly true for MR imaging. It also shows that imaging has to be applied correctly in order to be effective. In part one, the role of imaging prior to the start of treatment is discussed. The role of FDG PET-CT for the detection of metastatic lymph nodes is examined in chapter 2. Metastatic lymph nodes are routinely diagnosed using cytology acquired by USgFNAC. However, in patients that already received a PET-CT, for example to detect distant metastases, some information on the status of the lymph nodes is already available. By using the information freely available from the PET-CT around half of all lymph nodes could be spared an unnecessary USgFNAC examination. In chapter 3, the power of DW-MRI in the delineation process is examined. Although the conformity of the delineations was good, indicating that DW-MRI could be helpful during the pretreatment delineation phase, we also saw clear instances with a different interpretation of the images. Chapter 4 introduces ADC as a quantitative measurement. We show that the TNM stage, is significantly more powerful as a prognostic factor than pretreatment ADC. Part two starts by looking into ADC and in particular the change in ADC as it is measured during treatment. A prospective trial (the PREDICT trial) is described in chapter 5. PREDICT has the primary aim of predicting treatment outcome of HNSCC patients using the change in ADC induced by the radiation therapy. Chapter 6 illustrates a potential issue with MRI tumor identification and delineation during treatment. The change in the appearance of tumors on T2 weighted imaging hinders delineation and consequently reduces interobserver agreement. The most effective way to address this issue is probably to create clear and easy to follow guidelines on the delineation of tumors during treatment. In the last part of this thesis, part 3, imaging in the posttreatment phase is presented. Chapter 7 discusses a prospective comparative study of MRI with diffusion weighted sequences and PET-CT, the RETURNED study. Both are used to detect local recurrence. The diagnosis of recurrent HNSCC is significantly more challenging than the diagnosis of primary disease. This is due to the difficulty of differentiating between post treatment effects and recurrent tumor. In the study, MRI and PET-CT were both able to detect recurrences with an accuracy of around 70%. However, MRI showed a higher specificity but a lower sensitivity than PET-CT. Unfortunately, by adding the two modalities together the accuracy of detection did not improve much. Therefore we advocate that PET-CT, already routinely used for recurrence detection, should remain the modality of choice if there is clinical suspicion of recurrent tumor. A reason for the lack of accuracy of the MRI with diffusion weighted images is sought in chapter 8. Here, ten radiologist tried to determine if the MRI images of ten RETURNED patients showed a local recurrence or local control. The interobserver agreement was moderate. Other studies reported also a similar interobserver agreement for PET-CT and also the presence of easy and difficult cases. Perhaps that MRI examinations performed at regular intervals could improve the detection of recurrent MRI, however this was not examined in this thesis. Finally, chapter 9 describes a framework for implementing MRI in the radiotherapy process. This is relevant as innovations in the field resulted in hybrid radiotherapy and MRI devices that are currently being introduced to the clinic. It provides answers to questions a radiation oncologist or clinical physicist might have when introducing MRI for HNSCC radiotherapy treatment in their institutions
New developments in sentinel lymph node biopsy for early-stage oral cancer
No full textIn 2007, sentinel lymph node biopsy (SLNB) was applied for the first time in the Netherlands in a patient with early-stage oral cavity carcinoma without any signs of lymph node metastasis on clinical and radiological examination (clinically negative neck). In the following years, SLNB was increasingly applied in most Dutch head and neck cancer centers, on account of its less invasive nature compared to an elective neck dissection, as well as its ability to detect individual lymphatic drainage patterns. In doing so, SLNB is able to reveal aberrant lymphatic drainage and detect any lymph node metastases beyond the cervical nodal levels generally addressed by elective neck dissection. As a result, elective neck dissection was gradually abandoned as a treatment strategy for the clinically negative neck in patients with early-stage oral cancer. However, challenges remain for SLNB, especially in oral cancer due to the complex lymphatic system and abundance of lymph nodes in the neck. The main limitations of SLNB in oral cancer arise from the relatively low resolution of lymphoscintigraphy: an imaging technique that is able to assess the lymphatic drainage pattern of a tumor by injecting a radioactive tracer around the respective tumor. In situations where sentinel lymph nodes (SLNs) are located in close vicinity of the primary tumor, the radioactivity of the injection site can conceal the activity in nearby SLNs, making them undetectable. This particular circumstance, known as the shine-through phenomenon, considerably increases the risk of missing metastatic SLNs. Especially tumor subsites with close spatial relation to SLNs, such as the floor-of-mouth or vestibule-of-mouth, are prone to the shine-through phenomenon. As a consequence, patients may be incorrectly staged negative for the presence of nodal disease (i.e., false-negative outcome), thereby erroneously omitting the treatment required for the regional nodal basin. In addition, often multiple lymph nodes with radioactive uptake (i.e., hotspots) are revealed on lymphoscintigraphy. Although multiple true SLNs exist in many oral cancer patients, some hotspots may actually represent irrelevant higher echelon nodes. Falsely considering higher echelon nodes as SLNs can induce unnecessary surgical exploration of the neck, with its accompanying morbidity and risk of complications, which may hamper a complementary neck dissection in case of metastatic involvement of SLNs. Moreover, mistakenly designating SLNs as higher echelon nodes can lead to the neglect of true SLNs that are potentially harboring metastases. Considering that any untreated nodal metastasis will inevitably develop into clinical manifestation of disease, which usually entails more comprehensive surgery as well as more frequently adjuvant radiotherapy and even reduced chances of survival, there is a need for technological advancements to overcome these limitations of SLNB in oral cancer. This thesis is dedicated to improving the accuracy of SLNB and thereby improving the prognosis and quality-of-life for patients with early-stage oral cancer and a clinically negative neck. To that end, several new techniques for SLNB were investigated: SLNB with [99mTc]Tc-tilmanocept as tracer, MR lymphography with gadobutrol, CT lymphography with Lipidiol® and PET/CT lymphoscintigraphy with [68Ga]Ga-tilmanocept
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