Richard P. Meijer

Dr. Richard P. Meijer

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Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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4 December 2019 in BJU International
Verified
Journal Article
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JBJoost M. Blok
Joost M. Blok
IPIlse Pluim
Ilse Pluim
GDGedske Daugaard
Gedske Daugaard
TWThomas Wagner
Thomas Wagner
KJKatarzyna Jóźwiak
Katarzyna Jóźwiak
SHSimon Horenblas
Simon Horenblas
Objective: To systematically review the literature on the prognostic value of lymphovascular invasion (LVI) and embryonal carcinoma (EC) for occult metastatic disease in clinical stage I nonseminomatous germ cell tumour (CS I NSGCT). Materials and methods: The PubMed, Embase (OVID) and SCOPUS databases were searched up to March 2019. Studies reporting on the association between LVI and/or EC and occult metastatic disease were considered for inclusion. The quality and risk of bias were evaluated by the Quality in Prognosis Studies tool. Results: We screened 5287 abstracts and 207 full‐text articles. We included 35 studies in the narrative synthesis and 24 studies in a meta‐analysis. LVI showed the strongest effect. Pooled rates of occult metastasis were 47.5% and 16.9% for LVI‐positive and LVI‐negative patients, respectively (odds ratio [OR] 4.33, 95% confidence interval [CI] 3.55–5.30; P < 0.001). Pooled rates of occult metastasis were 33.2% for EC presence and 16.2% for EC absence (OR 2.49, 95% CI 1.64–3.77; P < 0.001). Pooled rates of occult metastasis were 40.0% for EC >50% and 20.0% for EC <50% (OR 2.62, 95% CI 1.93–3.56; P < 0.001). Conclusions: LVI is the strongest risk factor for relapse. The prognostic value of EC is high, but there is no common agreement on how to define this risk factor. Both EC presence and EC >50% have similar ORs for occult metastasis. This shows that the assessment of EC presence is sufficient for the classification of EC.

27 October 2021 in Cancers
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RFRachel Flach
Rachel Flach
PWPeter-Paul Willemse
Peter-Paul Willemse
BSBritt B. M. Suelmann
Britt B. M. Suelmann
IDIvette A. G. Deckers
Ivette A. G. Deckers
TJTrudy N. Jonges
Trudy N. Jonges
RMRichard P. Meijer
Richard P. Meijer
Purpose: Our aim was to analyze grading variation between pathology laboratories and between pathologists within individual laboratories using nationwide real-life data. Methods: We retrieved synoptic (n = 13,397) and narrative (n = 29,377) needle biopsy reports from the Dutch Pathology Registry and prostate-specific antigen values from The Netherlands Cancer Registration for prostate cancer patients diagnosed between January 2017 and December 2019. We determined laboratory-specific proportions per histologic grade and unadjusted odds ratios (ORs) for International Society of Urological Pathologists Grades 1 vs. 2–5 for 40 laboratories due to treatment implications for higher grades. Pathologist-specific proportions were determined for 21 laboratories that consented to this part of analysis. The synoptic reports of 21 laboratories were used for analysis of case-mix correction for PSA, age, year of diagnosis, number of biopsies and positive cores. Results: A total of 38,321 reports of 35,258 patients were included. Grade 1 ranged between 19.7% and 44.3% per laboratory (national mean = 34.1%). Out of 40 laboratories, 22 (55%) reported a significantly deviant OR, ranging from 0.48 (95% confidence interval (CI) 0.39–0.59) to 1.54 (CI 1.22–1.93). Case-mix correction was performed for 10,294 reports, altering the status of 3/21 (14%) laboratories, but increasing the observed variation (20.8% vs. 17.7%). Within 15/21 (71%) of laboratories, significant inter-pathologist variation existed. Conclusion: Substantial variation in prostate cancer grading was observed between and within Dutch pathology laboratories. Case-mix correction did not explain the variation. Better standardization of prostate cancer grading is warranted to optimize and harmonize treatment.


1 August 2019 in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
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Journal Article
Open access
MPMax Peters
Max Peters
MSMarieke J. van Son
Marieke J. van Son
MMMarinus A. Moerland
Marinus A. Moerland
LKLinda G.W. Kerkmeijer
Linda G.W. Kerkmeijer
WEWietse S.C. Eppinga
Wietse S.C. Eppinga
JZJochem R.N. van der Voort van Zijp
Jochem R.N. van der Voort van Zijp
For the treatment of localized prostate cancer, focal therapy has the potential to cure with fewer side effects than traditional whole-gland treatments. We report an update on toxicity, quality of life (QoL), and tumor control in our magnetic resonance imaging (MRI)-guided ultrafocal high-dose-rate brachytherapy cohort. Disease status was evaluated by systematic biopsies and 3T multiparametric MRI. The brachytherapy implant procedure under fused transrectal ultrasound/MRI guidance was followed by a 1.5 T MRI for contour adjustments and catheter position verification. A single dose of 19 Gy was delivered to the tumor with a margin of 5 mm. Genitourinary (GU) toxicity, gastrointestinal (GI) toxicity, and erectile dysfunction (ED) were graded with the Common Terminology Criteria for Adverse Events version 4.0. QoL was measured with RAND-36, European Organisation for Research and Treatment of Cancer QLQ-C30 and PR25. International Prostate Symptom Scores and International Index of Erectile Function scores were obtained. Prostate-specific antigen level was monitored, with biochemical recurrence defined as nadir + 2 ng/mL (Phoenix). Thirty patients with National Comprehensive Cancer Network low- (13%) to intermediate-risk (87%) prostate cancer were treated between May 2013 and April 2016. Median follow-up was 4 years. Median age was 71 years (interquartile range, 68-73) and median initial prostate-specific antigen level was 7.3 ng/mL (5.2-8.1). Maximum Gleason score was 4 + 3 = 7 (in 2 patients). All tumors were radiologic (MRI) stage T2. No grade >2 GU or >1 GI toxicity occurred. International Prostate Symptom Scores only deteriorated temporarily. Mild pretreatment ED deteriorated to moderate/severe ED in 50% of patients. Long-term clinically relevant QoL deterioration was seen in sexual activity and tiredness, whereas emotional and cognitive functioning improved. At 4 years, biochemical disease-free survival was 70% (95% confidence interval, 52%-93%), metastases-free survival was 93% (85%-100%), and overall survival was 100%. Of intraprostatic recurrences, 7 of 9 were out of field. Ultrafocal high-dose-rate brachytherapy conveys minimal GU or GI toxicity and has a marginal effect on QoL. An early decline in erectile function was seen. Tumor control outcomes are poor (biochemical disease-free survival of 70% [52%-93%] at 4 years), most likely as a result of poor patient selection.

15 December 2023 in British Journal of Cancer
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BVBastiaan J. Viergever
Bastiaan J. Viergever
DRDaniëlle A. E. Raats
Daniëlle A. E. Raats
VGVeerle Geurts
Veerle Geurts
JMJasper Mullenders
Jasper Mullenders
TJTrudy N. Jonges
Trudy N. Jonges
RMRichard P. Meijer
Richard P. Meijer
Background: Bladder cancer is one of the most common cancer types worldwide. Generally, research relies on invasive sampling strategies. Methods: Here, we generate bladder cancer organoids directly from urine (urinoids). In this project, we establish 12 urinoid lines from 22 patients with non-muscle and muscle-invasive bladder tumours, with an efficiency of 55%. Results: The histopathological features of the urinoids accurately resemble those of the original bladder tumours. Genetically, there is a high concordance of single nucleotide polymorphisms (92.56%) and insertions & deletions (91.54%) between urinoids and original tumours from patient 4. Furthermore, these urinoids show sensitivity to bladder cancer drugs, similar to their tissue-derived organoid counterparts. Genetic analysis of longitudinally generated tumoroids and urinoids from one patient receiving systemic immunotherapy, identify alterations that may guide the choice for second-line therapy. Successful treatment adaptation was subsequently demonstrated in the urinoid setting. Conclusion: Therefore, urinoids can advance precision medicine in bladder cancer as a non-invasive platform for tumour pathogenesis, longitudinal drug-response monitoring, and therapy adaptation.

11 November 2018 in BJU International
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Journal Article
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JBJoost M. Blok
Joost M. Blok
JKJ. Martijn Kerst
J. Martijn Kerst
EVErik Vegt
Erik Vegt
OBOscar R. Brouwer
Oscar R. Brouwer
RMRichard P. Meijer
Richard P. Meijer
SHSimon Horenblas
Simon Horenblas
Objectives: To report the long‐term results of the sentinel node (SN) approach in patients with clinical stage I testicular tumours in our facility. Patients and Methods: We conducted an analysis of 27 consecutive patients suspected of clinical stage I testicular germ cell tumour (TGCT) and treated with an SN procedure at our tertiary referral centre. SNs were identified using lymphoscintigraphy with or without single‐photo‐emission computed tomography with CT (SPECT/CT). Patients underwent laparoscopic retroperitoneal SN excision with inguinal orchiectomy. Patients with a tumour‐positive SN underwent adjuvant treatment. Follow‐up was conducted according to then‐current guidelines. Results: In two patients, no SNs were visualized on scintigraphy. In the remaining 25 patients, a median (range) of 3 (1–4) SNs per patient were removed. Two patients showed no malignancy on histopathological examination of the testis. Of the 23 patients diagnosed with TGCT (16 seminomas, seven non‐seminomas), three (13.0%) had occult metastatic disease. All 23 patients were without evidence of disease at a median (range) follow‐up of 63.9 (29.0–143.4) months. Conclusion: The SN procedure allows early identification of patients with occult metastatic disease in clinical stage I TGCT, enabling early treatment.