Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Birgit I. Witte is active.

Publication


Featured researches published by Birgit I. Witte.


International Journal of Cancer | 2013

Increasing prevalence rates of HPV attributable oropharyngeal squamous cell carcinomas in the Netherlands as assessed by a validated test algorithm

C. René Leemans; Elisabeth Bloemena; Daniëlle A.M. Heideman; Boudewijn J. M. Braakhuis; Albertus T. Hesselink; Birgit I. Witte; Robert J. Baatenburg de Jong; Chris J. L. M. Meijer; Peter J.F. Snijders; Ruud H. Brakenhoff

Human papillomavirus (HPV) infection has been etiologically linked to oropharyngeal squamous cell carcinoma (OPSCC). The prevalence of HPV‐positive OPSCC varies between studies, ranging from 20 to 90%. This may be related to the lack of a standardized HPV detection assay as well as to the time period in which HPV prevalence is investigated, as rising incidence rates are reported over the last decades. Here, we validated our previously defined test algorithm for HPV detection in formalin‐fixed paraffin‐embedded (FFPE) tumor specimen consisting of p16INK4A immunostaining followed by high‐risk HPV DNA detection by GP5+/6+ PCR on the positive cases (Smeets et al., Int J Cancer 2007;121:2465–72). In addition, we analyzed HPV prevalence rates in OPSCCs in the years 1990–2010. The test algorithm was validated on a consecutive series of 86 OPSCCs collected during 2008–2011, of which both fresh frozen and FFPE samples were available. We performed HPV‐E6 RT‐PCR on the frozen samples as gold standard and applied the algorithm to the corresponding FFPE samples. The test algorithm showed an accuracy of 98%. Using the validated algorithm, we determined the presence of an oncogenic HPV infection in 240 OPSCCs of patients diagnosed in the years 1990–2010 at our center. A significant increase in the proportion of HPV‐positive samples was observed, from 5.1% in 1990 to 29.0% in 2010 (p = 0.001). In conclusion, we confirmed the accuracy of the test algorithm for HPV detection in FFPE tumor specimen and we found a significant increase in the prevalence of HPV in OPSCC over the last two decades at our center.


Modern Pathology | 2012

Reproducibility of histopathological subtypes and invasion in pulmonary adenocarcinoma. An international interobserver study

Mary Beth Beasley; Alain C. Borczuk; Elisabeth Brambilla; Lucian R. Chirieac; Sanja Dacic; Douglas B. Flieder; Adi F. Gazdar; Kim R. Geisinger; Philip Hasleton; Yuichi Ishikawa; Keith M. Kerr; Sylvie Lantejoul; Yoshiro Matsuno; Yuko Minami; Andre L. Moreira; Noriko Motoi; Andrew G. Nicholson; Masayuki Noguchi; Daisuke Nonaka; Giuseppe Pelosi; Iver Petersen; Natasha Rekhtman; Victor L. Roggli; William D. Travis; Ming S. Tsao; Ignacio I. Wistuba; Haodong Xu; Yasushi Yatabe; Maureen F. Zakowski; Birgit I. Witte

Histological subtyping of pulmonary adenocarcinoma has recently been updated based on predominant pattern, but data on reproducibility are required for validation. This study first assesses reproducibility in subtyping adenocarcinomas and then assesses further the distinction between invasive and non-invasive (wholly lepidic) pattern of adenocarcinoma, among an international group of pulmonary pathologists. Two ring studies were performed using a micro-photographic image-based method, evaluating selected images of lung adenocarcinoma histologic patterns. In the first study, 26 pathologists reviewed representative images of typical and ‘difficult’ histologic patterns. A total number of scores for the typical patterns combined (n=94) and the difficult cases (n=21) were 2444 and 546, respectively. The mean kappa score (±s.d.) for the five typical patterns combined and for difficult cases were 0.77±0.07 and 0.38±0.14, respectively. Although 70% of the observers identified 12–65% of typical images as single pattern, highest for solid and least for micropapillary, recognizing the predominant pattern was achieved in 92–100%, of the images except for micropapillary pattern (62%). For the second study on invasion, identified as a key problem area from the first study, 28 pathologists submitted and reviewed 64 images representing typical as well as ‘difficult’ examples. The kappa for typical and difficult cases was 0.55±0.06 and 0.08±0.02, respectively, with consistent subdivision by the same pathologists into invasive and non-invasive categories, due to differing interpretation of terminology defining invasion. In pulmonary adenocarcinomas with classic morphology, which comprise the majority of cases, there is good reproducibility in identifying a predominant pattern and fair reproducibility distinguishing invasive from in-situ (wholly lepidic) patterns. However, more precise definitions and better education on interpretation of existing terminology are required to improve recognition of purely in-situ disease, this being an area of increasing importance.


Annals of the Rheumatic Diseases | 2013

A prediction rule for the development of arthritis in seropositive arthralgia patients

Lotte A van de Stadt; Birgit I. Witte; Wouter H Bos; Dirkjan van Schaardenburg

Objective To predict the development of arthritis in anticyclic citrullinated peptide antibodies and/or IgM rheumatoid factor positive (seropositive) arthralgia patients. Methods A prediction rule was developed using a prospective cohort of 374 seropositive arthralgia patients, followed for the development of arthritis. The model was created with backward stepwise Cox regression with 18 variables. Results 131 patients (35%) developed arthritis after a median of 12 months. The prediction model consisted of nine variables: Rheumatoid Arthritis in a first degree family member, alcohol non-use, duration of symptoms <12 months, presence of intermittent symptoms, arthralgia in upper and lower extremities, visual analogue scale pain ≥50, presence of morning stiffness ≥1 h, history of swollen joints as reported by the patient and antibody status. A simplified prediction rule was made ranging from 0 to 13 points. The area under the curve value (95% CI) of this prediction rule was 0.82 (0.75–0.89) after 5 years. Harrells C (95% CI) was 0.78 (0.73–0.84). Patients could be categorised in three risk groups: low (0–4 points), intermediate (5–6 points) and high risk (7–13 points). With the low risk group as a reference, the intermediate risk group had a hazard ratio (HR; 95% CI) of 4.52 (2.42–8.77) and the high risk group had a HR of 14.86 (8.40–28.32). Conclusions In patients presenting with seropositive arthralgia, the risk of developing arthritis can be predicted. The prediction rule that was made in this patient group can help (1) to inform patients and (2) to select high-risk patients for intervention studies before clinical arthritis occurs.


Journal of Hepatology | 2013

Relapse is almost universal after withdrawal of immunosuppressive medication in patients with autoimmune hepatitis in remission

Nicole M.F. van Gerven; Bart J. Verwer; Birgit I. Witte; Bart van Hoek; Minneke J. Coenraad; Karel J. van Erpecum; Ulrich Beuers; Henk R. van Buuren; Rob A. de Man; Joost P. H. Drenth; Jannie W. den Ouden; Robert C. Verdonk; Ger H. Koek; Johannes T. Brouwer; Maureen M. J. Guichelaar; Chris Jj Mulder; Karin M.J. van Nieuwkerk; Gerd Bouma

BACKGROUND & AIMS Current treatment strategies in autoimmune hepatitis (AIH) include long-term treatment with corticosteroids and/or azathioprine. Here we determined the risk of relapse after drug withdrawal in patients in long-term remission and factors associated with such a relapse. METHODS A total of 131 patients (out of a cohort including 844 patients) from 7 academic and 14 regional centres in the Netherlands were identified in whom treatment was tapered after at least 2 years of clinical and biochemical remission. Relapse was defined as alanine-aminotransferase levels (ALT) three times above the upper limit of normal and loss of remission as a rising ALT necessitating the reinstitution of drug treatment. RESULTS During follow-up, 61 (47%) patients relapsed and 56 (42%) had a loss of remission. In these 117 patients, 60 patients had fully discontinued medication whereas 57 patients were still on a withdrawal scheme. One year after drug withdrawal, 59% of the patients required retreatment, increasing to 73% and 81% after 2 and 3 years, respectively. Previous combination therapy of corticosteroids and azathioprine, a concomitant autoimmune disease and younger age at time of drug withdrawal were associated with an increased risk of relapse. Subsequent attempts for discontinuation after initial failure in 32 patients inevitably resulted in a new relapse. CONCLUSIONS This retrospective analysis indicates that loss of remission or relapse occurs in virtually all patients with AIH in long-term remission when immunosuppressive therapy is discontinued. These findings indicate a reluctant attitude towards discontinuation of immunosuppressive treatment in AIH patients.


Scandinavian Journal of Gastroenterology | 2014

Epidemiology and clinical characteristics of autoimmune hepatitis in the Netherlands

N. M. F. van Gerven; Bart J. Verwer; Birgit I. Witte; K.J. van Erpecum; H. R. van Buuren; I. Maijers; Arjan P. Visscher; E.C. Verschuren; B. van Hoek; Minneke J. Coenraad; U. Beuers; R. A. de Man; J.P.H. Drenth; J. den Ouden; Robert C. Verdonk; Ger H. Koek; J. T. Brouwer; Maureen M. J. Guichelaar; J.M. Vrolijk; C. J. J. Mulder; C. M. J. van Nieuwkerk; Gerd Bouma

Abstract Background and aims. Epidemiological data on autoimmune hepatitis (AIH) are scarce. In this study, we determined the clinical and epidemiological characteristics of AIH patients in the Netherlands (16.7 million inhabitants). Methods. Clinical characteristics were collected from 1313 AIH patients (78% females) from 31 centers, including all eight academic centers in the Netherlands. Additional data on ethnicity, family history and symptoms were obtained by the use of a questionnaire. Results. The prevalence of AIH was 18.3 (95% confidential interval [CI]: 17.3–19.4) per 100,000 with an annual incidence of 1.1 (95% CI: 0.5–2) in adults. An incidence peak was found in middle-aged women. At diagnosis, 56% of patients had fibrosis and 12% cirrhosis in liver biopsy. Overall, 1% of patients developed HCC and 3% of patients underwent liver transplantation. Overlap with primary biliary cirrhosis and primary sclerosing cholangitis was found in 9% and 6%, respectively. The clinical course did not differ between Caucasian and non-Caucasian patients. Other autoimmune diseases were found in 26% of patients. Half of the patients reported persistent AIH-related symptoms despite treatment with a median treatment period of 8 years (range 1–44 years). Familial occurrence was reported in three cases. Conclusion. This is the largest epidemiological study of AIH in a geographically defined region and demonstrates that the prevalence of AIH in the Netherlands is uncommon. Although familial occurrence of AIH is extremely rare, our twin data may point towards a genetic predisposition. The high percentage of patients with cirrhosis or fibrosis at diagnosis urges the need of more awareness for AIH.


International Journal of Cancer | 2014

Molecular characterization of p16‐immunopositive but HPV DNA‐negative oropharyngeal carcinomas

Peter J.F. Snijders; Derakshan Beekzada; Boudewijn J. M. Braakhuis; Arjen Brink; Daniëlle A.M. Heideman; Albertus T. Hesselink; Birgit I. Witte; Elisabeth Bloemena; Robert J. Baatenburg-De Jong; C. René Leemans; Ruud H. Brakenhoff

Recent studies have reported that p16 protein overexpression qualifies as a surrogate marker identifying an oncogenic human papillomavirus (HPV) infection in oropharyngeal squamous cell carcinoma (OPSCC). However, there is still a percentage of OPSCCs that are positive for p16 immunohistochemistry (p16 IHC) but lack HPV DNA. The objective of this study was to characterize this group at the molecular level by performing sensitive HPV DNA‐ and RNA‐based PCR methods and genetic profiling. All patients diagnosed with an OPSCC in the period 2000–2006 in two Dutch university medical centers were included (n = 841). The presence of HPV in a tumor sample was tested by p16 IHC followed by an HPV DNA GP5+/6+ PCR. p16 IHC scored positive in 195 samples, of which 161 were HPV DNA‐positive and 34 (17%) HPV DNA‐negative. In the latter group, a SPF10‐LiPA25 assay, an HPV16 type‐specific E7 PCR and an E6 mRNA RT‐PCR were performed. Next, ten of these cases were further analyzed for loss of heterozygosity (LOH) of 15 microsatellite markers at chromosome arms 3p, 9p and 17p. Of the 34 p16‐positive but PCR‐negative OPSCCs, two samples tested positive by SPF10 assay, HPV16 E7 PCR and HPV16 E6 mRNA RT‐PCR. Three samples tested positive by SPF10 assay but negative by the HPV16‐specific assays. Nine of ten cases that were tested for LOH showed a genetic pattern comparable to that of HPV‐negative tumors. This study categorizes p16‐positive but HPV DNA‐negative OPSCCs as HPV‐negative tumors based on genetic profiling. This study highlights the importance of performing HPV testing in addition to p16 IHC for proper identification of HPV‐associated OPSCCs.


British Journal of Cancer | 2013

Molecular sputum analysis for the diagnosis of lung cancer

A J Hubers; C F M Prinsen; Gabriella Sozzi; Birgit I. Witte

Lung cancer is the leading cause of cancer mortality rate worldwide, mainly because of the presence of metastatic disease at the time of diagnosis. Early detection of lung cancer improves prognosis, and towards this end, large screening trials in high-risk individuals have been conducted since the past century. Despite all efforts, the need for novel (complementary) lung cancer diagnostic and screening methods still exists. In this review, we focus on the assessment of lung cancer-related biomarkers in sputum in the past decennium. Besides cytology, mutation and microRNA analysis, special attention has been paid to DNA promoter hypermethylation, of which all available literature is summarised without time restriction. A model is proposed to aid in the distinction between diagnostic and risk markers. Research on the use of sputum for non-invasive detection of early-stage lung cancer has brought new insights and advanced molecular techniques. The sputum shows a promising potential for routine diagnostic and possibly screening purposes.


Oral Oncology | 2013

Prospective evaluation of health-related quality of life in long-term oral and oropharyngeal cancer survivors and the perceived need for supportive care

Inge M. Oskam; Irma M. Verdonck-de Leeuw; Neil K. Aaronson; Birgit I. Witte; Remco de Bree; P. Doornaert; Johannes A. Langendijk; C. René Leemans

PURPOSE To evaluate long-term changes in health related quality of life (HRQOL) in oral/oropharyngeal cancer survivors and their need for and use of supportive care. METHODS Between 1999 and 2001, 80 advanced oral or oropharyngeal cancer patients treated with free-flap reconstruction and postoperative radiotherapy were included in a prospective study of whom 27 patients were long-term survivors (mean 9.2 years, range 8-11 years). The HRQOL of 26 patients (response rate 96%) was assessed with the EORTC QLQ-C30 and QLQ-H&N35 questionnaires at four points in time: pretreatment (baseline), and at 6 months, 12 months (short term) and 8-11 years (long-term) follow up. A study specific questionnaire was developed to evaluate the need for and use of supportive care (allied health services, peer contact, psychosocial care, and complementary care) and was completed at the period of treatment and at long-term follow up. RESULTS A number of HRQOL domains worsened significantly (p < 0.01) in the long-term: emotional functioning, social functioning, swallowing, speech, taste/smell, dry mouth, sticky saliva and coughing assessed by the mixed effects statistical model. At time of treatment, the need for supportive care was the highest for a dental hygienist (77%), a physical therapist (73%), a speech therapist (42%), a dietician (38%), and a special diet (62%). At long-term follow up, the need for supportive care was limited to a dental hygienist (46%) and a physical therapist (23%). Only small differences were observed between the perceived need for and actual use of supportive care. CONCLUSION A range of HRQOL domains in head and neck cancer survivors were deteriorated in the long-term compared to baseline and to the first year after treatment. At time of treatment and less frequently at long-term follow up, patients reported needing and using a variety of supportive care services.


Oral Oncology | 2015

Histopathological grading of adenoid cystic carcinoma of the head and neck: analysis of currently used grading systems and proposal for a simplified grading scheme

Stijn van Weert; Isaäc van der Waal; Birgit I. Witte; C. René Leemans; Elisabeth Bloemena

BACKGROUND Histopathological grading of adenoid cystic carcinoma (ACC) is a controversial issue. It is generally agreed that solid type ACC has a relatively poor prognosis. However, the amount of solid regions within this often mixed type tumor that predicts a poor prognosis is not firmly established. Some authors stipulate that the presence of a solid component regardless of the amount is a poor prognosticator where others argue that the amount should be taken into consideration. Two grading systems most commonly used are those described by Perzin et al./Szanto et al. and Spiro et al., respectively. They report that prognosis of ACC is poor if >30% and >50% of the tumor volume has a solid growth pattern, respectively. MATERIAL AND METHODS The described grading systems are applied to a series of 81 surgically treated cases of ACC at the VU University Medical Center, Amsterdam, The Netherlands. Moreover, we introduced an alternative grading system, in which the presence of a solid component, irrespective of its amount, is considered. All three systems of grading were tested for inter-observer concordance and prediction of prognosis. RESULTS Inter-observer concordance for grading ACC according to Perzin et al./Szanto et al. and Spiro et al., proved to be moderate with Kappa Scores of 0.393 and 0.433, respectively. Our alternative grading system yielded inter-observer concordance with a Cohens kappa result of 0.990. All systems were comparable in discriminating patients with poor clinical outcome. Histopathological grade proved to be an independent prognosticator. CONCLUSION The presence of any solid component in ACC is a negative prognosticator, and can histopathologically be diagnosed with a high reliability. These results suggest to merely register the presence or absence of a solid tumor component since its inter-observer variability is very low, its reproducibility is high and its predictive value is comparable to the traditional grading systems used.


Annals of Statistics | 2010

Maximum smoothed likelihood estimation and smoothed maximum likelihood estimation in the current status model

Piet Groeneboom; Geurt Jongbloed; Birgit I. Witte

We consider the problem of estimating the distribution function, the density and the hazard rate of the (unobservable) event time in the current status model. A well studied and natural nonparametric estimator for the distribution function in this model is the nonparametric maximum likelihood estimator (MLE). We study two alternative methods for the estimation of the distribution function, assuming some smoothness of the event time distribution. The first estimator is based on a maximum smoothed likelihood approach. The second method is based on smoothing the (discrete) MLE of the distribution function. These estimators can be used to estimate the density and hazard rate of the event time distribution based on the plug-in principle.

Collaboration


Dive into the Birgit I. Witte's collaboration.

Top Co-Authors

Avatar

C. René Leemans

VU University Medical Center

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Peter J.F. Snijders

VU University Medical Center

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Elisabeth Bloemena

VU University Medical Center

View shared research outputs
Top Co-Authors

Avatar

Egbert F. Smit

Netherlands Cancer Institute

View shared research outputs
Top Co-Authors

Avatar

Femke Jansen

VU University Medical Center

View shared research outputs
Top Co-Authors

Avatar

C.R. Leemans

VU University Medical Center

View shared research outputs
Top Co-Authors

Avatar

Otto S. Hoekstra

VU University Medical Center

View shared research outputs
Researchain Logo
Decentralizing Knowledge