226 research outputs found
Optimal timing of harvest of two fish species with multiple gear types
In this paper a bioeconomic model is developed for a commercial fishery with multiple gear types in the case of two independent fish species. Where most bioeconomic fishery models focus on either multiple gear types or multiple species (mostly predator-prey relationships) this model combines both aspects for four gear types and two independent fish species. The objective of the paper is to find the optimal allocation of four gear types per period to obtain the highest net benefits while harvesting at a sustainable rate. This is done by developing a discrete time LP-model for a sole owner fishery, given a Total Allowable Catch for the two fish species. The model is applied to the Chippewas of Nawash First Nation commercial fishery in Lake Huron and Georgian Bay (Ontario, Canada). Sensitivity analyses are performed on price changes as well as on the average harvest levels per boat
Clinical auditing as an instrument to improve care for patients with ovarian cancer:The Dutch Gynecological Oncology Audit (DGOA)
Introduction: The Dutch Gynecological Oncology Audit (DGOA) was initiated in 2014 to serve as a nationwide audit, which registers the four most prevalent gynecological malignancies. This study presents the first results of clinical auditing for ovarian cancer in the Netherlands. Methods: The Dutch Gynecological Oncology Audit is facilitated by the Dutch Institute of Clinical Auditing (DICA) and run by a scientific committee. Items are collected through a web-based registration based on a set of predefined quality indicators. Results of quality indicators are shown, and benchmarked information is given back to the user. Data verification was done in 2016. Results: Between January 01, 2014 and December 31, 2018, 6535 patients with ovarian cancer were registered. The case ascertainment was 98.3% in 2016. The number of patients with ovarian cancer who start therapy within 28 days decreased over time from 68.7% in 2014 to 62.7% in 2018 (p < 0.001). The percentage of patients with primary cytoreductive surgery decreased over time (57.8%ā39.7%, P < 0.001). However, patients with complete primary cytoreductive surgery improved over time (53.5%ā69.1%, P < 0.001). Other quality indicators did not significantly change over time. Conclusion: The Dutch Gynecological Oncology Audit provides valuable data on the quality of care on patients with ovarian cancer in the Netherlands. Data show variation between hospitals with regard to pre-determined quality indicators. Results of ābest practicesā will be shared with all participants of the clinical audit with the aim of improving quality of care nationwide
Borderline ovarian tumor frozen section diagnoses with features suspicious of invasive cancer:a retrospective study
Abstract Background A frozen section diagnosis of a borderline ovarian tumor with suspicious features of invasive carcinoma (āat least borderlineā or synonymous descriptions) presents us with the dilemma of whether or not to perform a full ovarian cancer staging procedure. Quantification of this dilemma may help us with the issue of this clinical decision. The present study assessed and compared both the prevalence of straightforward borderline and āat least borderlineā frozen section diagnoses and the proportion of these women with a final histopathological diagnosis of invasive carcinoma, with a special interest in histologic subtypes. Methods A retrospective cohort study was performed in three hospitals in The Netherlands. All women that underwent ovarian surgery with perioperative frozen section evaluation in one of these hospitals between January 2007 and July 2018 were identified and included in case of a borderline or āat least borderlineā frozen section diagnosis and a borderline ovarian tumor or invasive carcinoma as a final diagnosis. Results A total of 223 women were included, of which 41 women (18.4%) were diagnosed with āat least borderlineā at frozen section. Thirteen of forty-one women (31.7%) following āat least borderlineā frozen section diagnosis and 14 of 182 women (7.7%) following a straightforward borderline frozen section diagnosis were diagnosed with invasive carcinoma at paraffin section evaluation (pā<ā0.001). When compared to straightforward borderline frozen section diagnoses, the proportion of women diagnosed with invasive carcinoma increased from 3.1 to 35.7% for serous tumors (pā=ā0.001), 10.0 to 21.7% for mucinous tumors (pā=ā0.129) and 50.0 to 75.0% (pā=ā0.452) in case of other histologic subtypes following an āat least borderlineā frozen section diagnosis. Conclusions Overall, when compared to women with a decisive borderline frozen section diagnosis, women diagnosed with āat least borderlineā frozen section diagnoses were found to have a higher chance of carcinoma upon final diagnosis (7.7% vs 31.7%). Especially in the serous subtype, full staging during initial surgery might be considered after preoperative consent to prevent a second surgical procedure or chemotherapy in unstaged women. Further studies are needed to evaluate whether additional sampling in case of an āat least borderlineā diagnosis may decrease the risk of surgical over-treatment
Frozen section diagnosis of borderline ovarian tumors with suspicious features of invasive cancer is a devil's dilemma for the surgeon:A systematic review and meta-analysis
Introduction Frozen section diagnoses of borderline ovarian tumors are not always straightforward and a borderline frozen section diagnosis with suspicious features of invasive carcinoma (reported as "at least borderline" or synonymous descriptions) presents us with the dilemma of whether or not to perform a full surgical staging procedure. By performing a systematic review and meta-analysis, the prevalence of straightforward borderline and "at least borderline" frozen section diagnoses, as well as proportion of patients with a final diagnosis of invasive carcinoma in these cases, were assessed and compared, as quantification of this dilemma may help us with the issue of this clinical decision. Material and methods PubMed, EMBASE and Cochrane library databases were searched and studies discussing "at least borderline" frozen section diagnoses were included in the review. Numbers of specific frozen section diagnoses and subsequent final histological diagnoses were extracted and pooled analysis was performed to compare the proportion of patients diagnosed with invasive carcinoma following borderline and "at least borderline" frozen section diagnoses, presented as risk ratio and risk difference with 95% confidence intervals (95% CI). Results Of 4940 screened records, eight studies were considered eligible for quantitative analysis. A total of 921 women was identified and 230 (25.0%) of these women were diagnosed with "at least borderline" ovarian tumor at the time of frozen section. Final histological diagnoses were reported in five studies, including 61 women with an "at least borderline" diagnosis and 290 women with a straightforward borderline frozen section diagnosis. Twenty-five of 61 women (41.0%) of the "at least borderline" group had invasive cancer at final diagnosis, compared with 28 of 290 women (9.7%) of the straightforward borderline frozen section group (risk difference -0.34, 95% CI -0.53 to -0.15; relative risk 0.25, 95% CI 0.13-0.50). Conclusions Women diagnosed with "at least borderline" frozen section diagnoses were found to have a higher chance of carcinoma upon final diagnosis when compared with women with a straightforward borderline frozen section diagnosis (41.0% vs 9.7%). Especially in the serous subtype, and after preoperative consent, full staging during initial surgery might be considered in these cases to prevent a second surgical procedure
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