| 1. |
- van Leeuwen, F., et al.
(author)
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Gaia Data Release 1 : Open cluster astrometry: Performance, limitations, and future prospects
- 2017
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
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Journal article (peer-reviewed)abstract
- Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods. Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed. Results. Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier Hipparcos-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters. Conclusions. The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the Hipparcos data, with clearly increased luminosities for older A and F dwarfs.
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| 2. |
- Loeb, Stacy, et al.
(author)
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Five-year Nationwide Follow-up Study of Active Surveillance for Prostate Cancer
- 2015
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In: European Urology. - : Elsevier BV. - 0302-2838 .- 1873-7560. ; 67:2, s. 233-238
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Journal article (peer-reviewed)abstract
- Background: Active surveillance (AS) is an important yet underutilized strategy to reduce prostate cancer (PCa) overtreatment. Objective: To examine the 5-yr outcomes of AS in a population-based setting. Design, setting, and participants: From the National Prostate Cancer Register of Sweden, we identified 11 726 men <= 70 yr diagnosed with very low-risk to intermediate-risk PCa from 2003 to 2007 who completed 5 yr of follow-up. Of these men, 1729 (15%) chose AS for the primary management strategy. Outcome measurements and statistical analysis: We calculated the probability of discontinuation of AS over time, and Cox proportional hazards models were used to determine factors associated with discontinuation. Reasons for discontinuation were assessed by data extraction from medical charts. Results and limitations: By 5 yr, 64% of the men remained on AS. Predictors of discontinuation were younger age, fewer comorbidities, more education, higher prostate-specific antigen (PSA), and clinical stage T2 disease; marital status did not predict discontinuation. In a subset with data on the reason for discontinuation (86%), 20% of men discontinued because of patient preference, 52% because of PSA progression, 24% because of biopsy progression, and 3% for other reasons. Conclusions: In a population-based setting, the majority of men remained on AS at 5 yr. However, one-fifth of the men who discontinued AS did so for nonbiologic reasons. Thus, there is a need for support and counseling for men to continue AS in the absence of signs of progression to improve adherence to AS and decrease overtreatment. Patient summary: Active surveillance (AS) is an important option to delay or avoid treatment for men with favorable prostate cancer features. This study shows that at 5 yr, 64% of men across an entire population remained on AS. We concluded that AS is a durable option and that counseling may be useful to promote adherence for men without progression.
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| 3. |
- Loeb, Stacy, et al.
(author)
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Immediate versus delayed prostatectomy : Nationwide population-based study
- 2016
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In: Scandinavian journal of urology. - : Informa UK Limited. - 2168-1805 .- 2168-1813. ; 50:4, s. 246-254
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Journal article (peer-reviewed)abstract
- Objective: The aim of this study was to compare the outcome of immediate versus delayed radical prostatectomy (RP) in men with low-grade prostate cancer. Materials and methods: The study included a nationwide population-based cohort in the National Prostate Cancer Register of Sweden, of 7608 men with clinically localized, biopsy Gleason score 6 prostate cancer who underwent immediate or delayed RP in 1997-2007. Multivariable models compared RP pathology, use of salvage radiotherapy and prostate cancer mortality based on timing of RP (< 1, 1-2 or > 2 years after diagnosis). Median follow-up was 8.1 years. Results: Men undergoing RP more than 2 years after diagnosis had a higher risk of Gleason upgrading [odds ratio 2.93, 95% confidence interval (CI) 2.34-3.68] and an increased risk of salvage radiotherapy [hazard ratio (HR) 1.90, 95% CI 1.41-2.55], but no significant increase in prostate cancer-specific mortality (HR 1.85, 95% CI 0.57-5.99). In competing risk analysis, 7 year prostate cancer-specific cumulative mortality was similar, at less than 1%, for immediate RP and active surveillance regardless of later intervention. Limitations of this study include the lack of data on follow-up biopsies and the limited follow-up time. Conclusion: Men undergoing RP more than 2 years after diagnosis had more adverse pathological features and second line therapy, highlighting the trade-off in deferring immediate curative therapy. However, men with delayed RP constitute a minority with higher risk cancer among the much larger group of low-risk men initially surveilled, and the overall risk of prostate cancer mortality at 7 years was similarly low with immediate RP or active surveillance.
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| 4. |
- Makarov, Danil V., et al.
(author)
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Prostate Cancer Imaging Trends After a Nationwide Effort to Discourage Inappropriate Prostate Cancer Imaging
- 2013
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In: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 105:17, s. 1306-1313
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Journal article (peer-reviewed)abstract
- Background Reducing inappropriate use of imaging to stage incident prostate cancer is a challenging problem highlighted recently as a Physician Quality Reporting System quality measure and by the American Society of Clinical Oncology and the American Urological Association in the Choosing Wisely campaign. Since 2000, the National Prostate Cancer Register (NPCR) of Sweden has led an effort to decrease national rates of inappropriate prostate cancer imaging by disseminating utilization data along with the latest imaging guidelines to urologists in Sweden. We sought to determine the temporal and regional effects of this effort on prostate cancer imaging rates. Methods We performed a retrospective cohort study among men diagnosed with prostate cancer from the NPCR from 1998 to 2009 (n = 99 879). We analyzed imaging use over time stratified by clinical risk category (low, intermediate, high) and geographic region. Generalized linear models with a logit link were used to test for time trend. Results Thirty-six percent of men underwent imaging within 6 months of prostate cancer diagnosis. Overall, imaging use decreased over time, particularly in the low-risk category, among whom the imaging rate decreased from 45% to 3% (P < .001), but also in the high-risk category, among whom the rate decreased from 63% to 47% (P < .001). Despite substantial regional variation, all regions experienced clinically and statistically (P < .001) significant decreases in prostate cancer imaging. Conclusions A Swedish effort to provide data on prostate cancer imaging use and imaging guidelines to clinicians was associated with a reduction in inappropriate imaging over a 10-year period, as well as slightly decreased appropriate imaging in high-risk patients. These results may inform current efforts to promote guideline-concordant imaging in the United States and internationally.
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