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Dive into the research topics where Saskia Bulk is active.

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Featured researches published by Saskia Bulk.


International Journal of Cancer | 2012

Evaluation of 14 triage strategies for HPV DNA-positive women in population-based cervical screening.

Dorien C. Rijkaart; Johannes Berkhof; Folkert J. van Kemenade; Veerle M.H. Coupé; Albertus T. Hesselink; Lawrence Rozendaal; Daniëlle A.M. Heideman; Ren e H.M.Verheijen; Saskia Bulk; Wim M. Verweij; Peter J.F. Snijders; Chris J. L. M. Meijer

High‐risk human papillomavirus (hrHPV) testing has a higher sensitivity but lower specificity than cytology for detection of high‐grade intraepithelial neoplasia (CIN). To avoid over‐referral to colposcopy and overtreatment, hrHPV‐positive women require triage testing and/or followup. A total of 25,658 women (30–60 years) enrolled in a population‐based cohort study had an adequate baseline Pap smear and hrHPV test. The end‐point was cumulative two‐year risk of CIN grade 3 or worse (CIN3+). In a post‐hoc analysis, fourteen triage/followup strategies for hrHPV‐positive women (n = 1,303) were evaluated for colposcopy referral rate, positive (PPV) and negative predictive value (NPV). Five strategies involved triage testing without a repeat test and nine strategies involved triage testing followed by one repeat testing. The tests were cytology, hrHPV, HPV16/18 genotyping and HPV16/18/31/33/45 genotyping. Results were adjusted for women in the cohort study who did not attend repeat testing. Of the strategies without repeat testing, combined cytology and HPV16/18/31/33/45 genotyping gave the highest NPV of 98.9% (95%CI 97.6–99.5%). The corresponding colposcopy referral rate was 58.1% (95%CI 55.4–60.8%). Eight of the nine strategies with retesting had an estimated NPV of at least 98%. Of those, cytology triage followed by cytology at 12 months had a markedly lower colposcopy referral rate of 33.4% (95%CI 30.2–36.7%) than the other strategies. The NPV of the latter strategy was 99.3% (95%CI 98.1–99.8%). Triage hrHPV‐positive women with cytology, followed by repeat cytology testing yielded a high NPV and modest colposcopy referral rate and appear to be the most feasible management strategy.


Journal of Clinical Pathology | 2004

The Dutch CISOE-A framework for cytology reporting increases efficacy of screening upon standardisation since 1996

Saskia Bulk; F. J. van Kemenade; Lawrence Rozendaal; C. J. L. M. Meijer

Aim: To describe the effect of introducing the CISOE-A framework for reporting cervical cytology results, including changes in repeat and referral advice in the Netherlands, on the efficacy of the screening programme. Changes in the distribution of cytological results, the detection rate of cervical intraepithelial neoplasia (CIN) lesions, and the detection rate of squamous cervical carcinoma are reported. Methods: The results of all gynaecology cytological and histological examinations, as registered in the nationwide database for histopathology and cytopathology (PALGA) from 1990 to 2000, were retrieved from seven laboratories in the greater Amsterdam area. Results: After the introduction of the CISOE-A classification, cytological results with equivocal diagnoses decreased significantly from 11.3% to 2.6%, without an increase in the percentages of moderate dyskaryosis or worse. During the study period, the detection rate of histologically diagnosed high grade CIN lesions increased significantly from 4.1 to 6.4/1000 smears, whereas there was no change in the detection rates of low grade lesions or invasive cervical cancer. Conclusions: The introduction of the new CISOE-A classification system resulted in a substantial decrease of equivocal results and repeat recommendations, without a decrease in the detection rate of high grade lesions, making the screening programme more efficacious.


British Journal of Cancer | 2006

Preferential risk of HPV16 for squamous cell carcinoma and of HPV18 for adenocarcinoma of the cervix compared to women with normal cytology in The Netherlands

Saskia Bulk; Johannes Berkhof; Nicole W.J. Bulkmans; G. D. Zielinski; Lawrence Rozendaal; F. J. van Kemenade; P. J. F. Snijders; C. J. L. M. Meijer

We present the type-distribution of high-risk human papillomavirus (HPV) types in women with normal cytology (n=1467), adenocarcinoma in situ (ACIS) (n=61), adenocarcinoma (n=70), and squamous cell carcinoma (SCC) (n=83). Cervical adenocarcinoma and ACIS were significantly more frequently associated with HPV18 (ORMH 15.0; 95% CI 8.6–26.1 and 21.8; 95% CI 11.9–39.8, respectively) than normal cytology. Human papillomavirus16 was only associated with adenocarcinoma and ACIS after exclusion of HPV18-positive cases (ORMH 6.6; 95% CI 2.8–16.0 and 9.4; 95% CI 2.8–31.2, respectively). For SCC, HPV16 prevalence was elevated (ORMH 7.0; 95% CI 3.9–12.4) compared to cases with normal cytology, and HPV18 prevalence was only increased after exclusion of HPV16-positive cases (ORMH 4.3; 95% CI 1.6–11.6). These results suggest that HPV18 is mainly a risk factor for the development of adenocarcinoma whereas HPV16 is associated with both SCC and adenocarcinoma.


International Journal of Cancer | 2005

Cervical cancer in the Netherlands 1989–1998: Decrease of squamous cell carcinoma in older women, increase of adenocarcinoma in younger women

Saskia Bulk; Otto Visser; Lawrence Rozendaal; René H.M. Verheijen; Chris J. L. M. Meijer

Cervical cancer is a preventable disease, occurring in relatively young women. In the Netherlands, population‐based cervical screening aims at women aged 30–60 years. We performed a population‐based study of the incidence of invasive cervical cancer in the Netherlands to evaluate trends, with emphasis on age at time of diagnosis. Histologic diagnosis was retrieved from the Netherlands Cancer Registry for all women residing in the Netherlands with invasive cervical cancer between January 1, 1989, and December 31, 1998. In this 10‐year period, the incidence rate of squamous cell carcinoma decreased significantly from 7.1/100,000 to 6.1/100,000 (p < 0.001), with the greatest decrease in women aged 60–74 (–5.5%). While the overall incidence rate of adenocarcinoma remained stable, it increased in women aged 15–29 (+15.8%) and in women aged 30–44 (+2.5%), though the number of cases was small. For squamous cell carcinoma, the incidence of stage II at diagnosis decreased most (–2.7%). There was no change in stage at diagnosis for adenocarcinoma. Most cases of cervical cancer, 60.5%, were detected between ages 30 and 60 years, i.e., the Dutch screening age interval. Cervical cancer in women below age 30 contributed 5.0% to the total incidence, with 3.0% occurring between ages 27 and 29. Thus, screening for cervical cancer in the Netherlands is associated with a decrease in the incidence of squamous cell carcinoma and adenocarcinoma incidence appears to be increasing in younger women.


Neurology | 2000

14-3-3 testing in diagnosing Creutzfeldt–Jakob disease A prospective study in 112 patients

A. W. Lemstra; M. T. van Meegen; J. P. Vreyling; P.H.S. Meijerink; Gerard H. Jansen; Saskia Bulk; Frank Baas; W.A. van Gool

Objective: To study the sensitivity and specificity of 14-3-3 testing in a prospective series of patients suspected of having Creutzfeldt-Jakob disease (CJD). Background: The 14-3-3 protein immunoassay on CSF has favorable test characteristics as a premortem diagnostic tool in CJD. However, the 14-3-3 protein is a normal cellular protein expressed in various tissues, and its presence in CSF reflects extensive destruction of brain tissue as in CJD, but also in ischemic stroke and meningoencephalitis. Methods: 14-3-3 was tested in the CSF of a prospective series of 110 consecutive patients suspected of having CJD. Results: The sensitivity was 97% and the specificity was 87% in this series. False-positive results were mainly caused by stroke and meningoencephalitis. Conclusion: The 14-3-3 protein is a highly sensitive and specific marker for CJD when used in the appropriate clinical context.


British Journal of Cancer | 2007

High-risk HPV type-specific clearance rates in cervical screening

Nicole W.J. Bulkmans; Johannes Berkhof; Saskia Bulk; Maaike C.G. Bleeker; F. J. van Kemenade; Lawrence Rozendaal; P. J. F. Snijders; Chris J. L. M. Meijer

We assessed clearance rates of 14 high-risk human papillomavirus (hrHPV) types in hrHPV-positive women with normal cytology and borderline/mild dyskaryosis (BMD) in a population-based cervical screening cohort of 44 102 women. The 6-month hrHPV type-specific clearance rates, that is, clearance of the same type as detected at baseline, in women with normal and BMD smears were 43% (95% confidence interval (CI) 39–47) and 29% (95% CI 24–34), respectively. Corresponding 18-month clearance rates were markedly higher, namely 65% (95% CI 60–69) and 41% (95% CI 36–47), respectively. The lowest clearance rates in women with normal cytology were observed for HPV16, HPV18, HPV31, and HPV33. Significantly reduced 18-month clearance rates at a significance level of 1% were observed for HPV16 (49%, 95% CI 41–59) and HPV31 (50%, 95% CI 39–63) in women with normal cytology, and for HPV16 (19%, 95% CI 12–29) in women with BMD. Among women who did not clear hrHPV, women with HPV16 persistence displayed an increased detection rate of ⩾CIN3 (normal P<0.0001; BMD, P=0.005). The type-specific differences in clearance rates indicate the potential value of hrHPV genotyping in screening programs. Our data support close surveillance (i.e. referral directly, or within 6 months) of women with HPV16 and are inconclusive for surveillance of women with HPV18, HPV31, and HPV33. For the other hrHPV-positive women, it seems advisable to adopt a conservative management with a long waiting period, as hrHPV clearance is markedly higher after 18 months than after 6 months and the risk for ⩾CIN3 is low.


Cancer Epidemiology, Biomarkers & Prevention | 2006

Human Papillomavirus Type–Specific 18-Month Risk of High-Grade Cervical Intraepithelial Neoplasia in Women with a Normal or Borderline/Mildly Dyskaryotic Smear

Johannes Berkhof; Nicole Wj Bulkmans; Maaike C.G. Bleeker; Saskia Bulk; Peter J.F. Snijders; Feja J. Voorhorst; Chris J. L. M. Meijer

Introduction: High-risk human papillomavirus (hrHPV) DNA testing is an increasingly used instrument in cervical cancer prevention along cervical cytology. The inclusion of hrHPV testing in cervical screening requires efficient management as many hrHPV infections are transient. We investigated the potential value of hrHPV genotyping in normal and borderline/mildly dyskaryotic (BMD) smears. Materials and Methods: From a screening population of 44,102 women in the Netherlands, we included hrHPV-positive women with a normal or BMD smear. We assessed the type-specific 18-month risk of high-grade cervical intraepithelial neoplasia (CIN). Results: In hrHPV-positive women, 18-month risk of CIN grade 3 or invasive cancer (≥CIN3) was 6% [95% confidence interval (95% CI), 4-9] after normal cytology and 20% (95% CI, 16-25) after BMD. If positive for HPV16, ≥CIN3 risks were 14% (95% CI, 9-21) and 37% (95% CI, 28-48), respectively. In the subset of hrHPV-positive women without HPV16, HPV18 was associated with an increased risk of high-grade CIN after normal cytology and HPV31 and HPV33 were associated with an increased risk, particularly after BMD. HPV16 and HPV18 were also associated with an increased risk of high-grade CIN in women with an hrHPV-positive normal baseline smear and a repeat normal smear at 6 months. Discussion: HrHPV-positive women without type 16, 18, 31, or 33 had a relatively low risk of high-grade CIN. Among women with baseline normal cytology and among women with a baseline and repeat normal smear, HPV16/18–positive women showed an increased risk of high-grade CIN. This warrants more aggressive management of HPV16/18–positive women compared with other hrHPV-positive women. (Cancer Epidemiol Biomarkers Prev 2006;15(7):1268–73)


British Journal of Cancer | 2012

HPV DNA testing in population-based cervical screening (VUSA-Screen study): results and implications.

Dorien C. Rijkaart; Johannes Berkhof; F. J. van Kemenade; Veerle M.H. Coupé; Lawrence Rozendaal; Daniëlle A.M. Heideman; Rhm Verheijen; Saskia Bulk; Wim M. Verweij; P. J. F. Snijders; C. J. L. M. Meijer

Background:Human papillomavirus (HPV) testing is more sensitive than cytology for detecting high-grade cervical intraepithelial neoplasia (CIN). We evaluated the performance of high-risk HPV (hrHPV) testing in routine screening.Methods:In all, 25 871 women (29–61) enrolled in our population-based cohort study were offered both cytology and hrHPV testing. High-risk HPV-positive women with normal cytology and an age-matched subcohort of hrHPV-negative women with normal cytology were invited for repeat testing after 1 and/or 2 years and were referred for colposcopy if they presented with abnormal cytology and/or a positive hrHPV test. The hrHPV-positive women with borderline or mild dyskaryosis (BMD) and all women with moderate dyskaryosis or worse (>BMD) were directly referred for colposcopy. Women with BMD and an hrHPV-negative test were advised to repeat cytology at 6 and 18 months and were referred for colposcopy if the repeat cytology test was abnormal. The main outcome measure was CIN grade 3 or worse (CIN3+). Results were adjusted for non-attendance at repeat testing.Results:The hrHPV-positive women with abnormal cytology had a CIN3+ risk of 42.2% (95% confidence interval (CI): 36.4–48.2), whereas the hrHPV-positive women with normal cytology had a much lower risk of 5.22% (95% CI: 3.72–7.91). In hrHPV-positive women with normal cytology, an additional cytology step after 1 year reduced the CIN3+ risk to only 1.6% (95% CI: 0.6–4.9) if the repeat test was normal. The CIN3+ risk in women with hrHPV-positive normal cytology was higher among women invited for the first time (29–33 years of age) (9.1%; 95% CI: 5.6–14.3) than among older women (3.0%; 95% CI: 1.5–5.5).Conclusion:Primary hrHPV screening with cytology triage in women aged ⩾30 years is an effective way to stratify women on CIN3+ risk and seems a feasible alternative to cytological screening. Repeat cytology after 1 year for hrHPV-positive women with normal cytology is however necessary before returning women to routine screening.


International Journal of Cancer | 2007

Risk of high-grade cervical intra-epithelial neoplasia based on cytology and high-risk HPV testing at baseline and at 6-months†

Saskia Bulk; Nicole W.J. Bulkmans; Johannes Berkhof; Lawrence Rozendaal; A. Joan P. Boeke; René H.M. Verheijen; Peter J.F. Snijders; Chris J. L. M. Meijer

Adding a test for high‐risk human papillomavirus (hrHPV) to cytological screening enhances the detection of high‐grade cervical intraepithelial neoplasia (≥CIN2), but data are required that enable long‐term evaluation of screening. We investigated the ≥CIN2 risk for women participating in population‐based screening as a function of hrHPV and cytology testing results at baseline and at 6 months. We included 2,193 women aged 30–60 years participating in a population‐based screening trial who received colposcopy or a repeat testing advice at baseline. The main endpoint was histologically confirmed ≥CIN2 diagnosed within 36 months. hrHPV testing was more sensitive than cytology for ≥CIN2 (relative sensitivity 1.4, 95%CI: 1.3–1.5; absolute sensitivity 94.1 and 68.0%, respectively). The 18‐month ≥CIN2 risks in women with a hrHPV‐positive smear and in women with abnormal cytology were similar (relative risk 0.9, 95%CI: 0.8–1.1). Women with HPV16 and/or HPV18 had a higher ≥CIN2 risk than other hrHPV‐positive women irrespective of the cytological grade. Repeat testing showed that both cytological regression and viral clearance were strongly associated with a decrease in ≥CIN2 risk. Notably, women who had a double negative repeat test at 6 months had a ≥CIN2 risk of only 0.2% (95%CI: 0.0–1.1) and hrHPV‐negative women with baseline borderline or mild dyskaryosis and normal cytology at 6 months had a ≥CIN2 risk of 0% (95%CI: 0.0–0.8). Using hrHPV and/or cytology testing, risk of ≥CIN2 can be assessed more accurately by repeat testing than single visit testing. Hence, when hrHPV testing is implemented, patient management with repeat testing is a promising strategy to control the number of referrals for colposcopy.


European Journal of Medical Genetics | 2014

Implementation of genomic arrays in prenatal diagnosis: The Belgian approach to meet the challenges

Olivier Vanakker; Catheline Vilain; Katrien Janssens; Nathalie Van der Aa; Guillaume Smits; Claude Bandelier; Bettina Blaumeiser; Saskia Bulk; Jean-Hubert Caberg; Anne De Leener; Marjan De Rademaeker; Thomy de Ravel; Julie Désir; A Destree; Annelies Dheedene; Stéphane Gaillez; Bernard Grisart; Ann-Cécile Hellin; Sandra Janssens; Kathelijn Keymolen; Björn Menten; Bruno Pichon; Marie Ravoet; Nicole Revencu; Sonia Rombout; Catherine Staessens; Ann Van Den Bogaert; Kris Van Den Bogaert; Joris Vermeesch; Frank Kooy

After their successful introduction in postnatal testing, genome-wide arrays are now rapidly replacing conventional karyotyping in prenatal diagnostics. While previous studies have demonstrated the advantages of this method, we are confronted with difficulties regarding the technology and the ethical dilemmas inherent to genomic arrays. These include indication for testing, array design, interpretation of variants and how to deal with variants of unknown significance and incidental findings. The experiences with these issues reported in the literature are most often from single centres. Here, we report on a national consensus approach how microarray is implemented in all genetic centres in Belgium. These recommendations are subjected to constant re-evaluation based on our growing experience and can serve as a useful tool for those involved in prenatal diagnosis.

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Dive into the Saskia Bulk's collaboration.

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Lawrence Rozendaal

VU University Medical Center

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C. J. L. M. Meijer

VU University Medical Center

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F. J. van Kemenade

VU University Medical Center

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Johannes Berkhof

VU University Medical Center

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Bruno Pichon

Université libre de Bruxelles

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Claude Bandelier

Université catholique de Louvain

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Julie Désir

Université libre de Bruxelles

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