Jan Willem B. De Groot

Dr. Jan Willem B. De Groot

Oncological Center Isala, Isala, Dokter van Heesweg 2, Zwolle 8025 AB, The Netherlands

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

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

Representative Publications

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1 December 2007 in Endocrine-Related Cancer
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Jan Willem B. De GrootJan Willem B. De Groot
Jan Willem B. De Groot
BRBart Rikhof
Bart Rikhof
JDJaap van Doorn
Jaap van Doorn
HBHenk J G Bilo
Henk J G Bilo
MAMaarten A Alleman
Maarten A Alleman
WGWinette T A van der Graaf
Winette T A van der Graaf
This review focuses on the tumour types and symptoms associated with non-islet cell tumour-induced hypoglycaemia (NICTH) as well as the pathogenesis, diagnosis and treatment of this rare paraneoplastic phenomenon. In addition, we report two illustrative cases of patients suffering from NICTH caused by a solid fibrous tumour and a haemangiopericytoma respectively. In the first case, NICTH resolved following complete resection of the tumour, but in the second case the patient needed long-term treatment aimed at controlling hypoglycaemia because of non-resectable metastases. Many tumour types have been associated with NICTH. The crucial event in the development of NICTH seems to be overexpression of the IGF-II gene by the tumour. NICTH is characterised by recurrent fasting hypoglycaemia and is associated with the secretion of incompletely processed precursors of IGF-II (‘big’-IGF-II) by the tumour. This induces dramatic secondary changes in the circulating levels of insulin, GH, IGF-I and IGF-binding proteins, resulting in an insulin-like hypoglycaemic activity of ‘big’-IGF-II.

1 January 2013 in Orphanet Journal of Rare Diseases
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JHJohannes Hofland
Johannes Hofland
LHLeo J. Hofland
Leo J. Hofland
PKPeter M van Koetsveld
Peter M van Koetsveld
JSJacobie Steenbergen
Jacobie Steenbergen
WHWouter W de Herder
Wouter W de Herder
RFRichard A. Feelders
Richard A. Feelders
Adrenal Cushing’s syndrome caused by ACTH-independent macronodular adrenocortical hyperplasia (AIMAH) can be accompanied by aberrant responses to hormonal stimuli. We investigated the prevalence of adrenocortical reactions to these stimuli in a large cohort of AIMAH patients, both in vivo and in vitro. In vivo cortisol responses to hormonal stimuli were studied in 35 patients with ACTH-independent bilateral adrenal enlargement and (sub-)clinical hypercortisolism. In vitro, the effects of these stimuli on cortisol secretion and steroidogenic enzyme mRNA expression were evaluated in cultured AIMAH and other adrenocortical cells. Arginine-vasopressin (AVP) receptor mRNA levels were determined in the adrenal tissues. Positive serum cortisol responses to stimuli were detected in 27/35 AIMAH patients tested, with multiple responses within individual patients occurring for up to four stimuli. AVP and metoclopramide were the most prevalent hormonal stimuli triggering positive responses in vivo. Catecholamines induced short-term cortisol production more often in AIMAH cultures compared to other adrenal cells. Short- and long-term incubation with AVP increased cortisol secretion in cultures of AIMAH cells. AVP also increased steroidogenic enzyme mRNA expression, among which an aberrant induction of CYP11B1. AVP type 1a receptor was the only AVPR expressed and levels were high in the AIMAH tissues. AVPR1A expression was related to the AVP-induced stimulation of CYP11B1. Multiple hormonal signals can simultaneously induce hypercortisolism in AIMAH. AVP is the most prevalent eutopic signal and expression of its type 1a receptor was aberrantly linked to CYP11B1 expression.

27 July 2020 in Cancers
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MKMonique van der Kooij
Monique van der Kooij
MWMarjolein Wetzels
Marjolein Wetzels
MAMaureen J.B. Aarts
Maureen J.B. Aarts
FBFranchette W.P.J. van Den Berkmortel
Franchette W.P.J. van Den Berkmortel
CBChristian U. Blank
Christian U. Blank
Ellen KapiteijnEllen Kapiteijn
Ellen Kapiteijn
Cutaneous melanoma is a common type of cancer in Adolescents and Young Adults (AYAs, 15–39 years of age). However, AYAs are underrepresented in clinical trials investigating new therapies and the outcomes from these therapies for AYAs are therefore unclear. Using prospectively collected nation-wide data from the Dutch Melanoma Treatment Registry (DMTR), we compared baseline characteristics, mutational profiles, treatment strategies, grade 3–4 adverse events (AEs), responses and outcomes in AYAs (n = 210) and older adults (n = 3775) who were diagnosed with advanced melanoma between July 2013 and July 2018. Compared to older adults, AYAs were more frequently female (51% versus 40%, p = 0.001), and had a better Eastern Cooperative Oncology Group performance status (ECOG 0 in 54% versus 45%, p = 0.004). BRAF and NRAS mutations were age dependent, with more BRAF V600 mutations in AYAs (68% versus 46%) and more NRAS mutations in older adults (13% versus 21%), p < 0.001. This finding translated in distinct first-line treatment patterns, where AYAs received more initial targeted therapy. Overall, grade 3–4 AE percentages following first-line systemic treatment were similar for AYAs and older adults; anti-PD-1 (7% versus 14%, p = 0.25), anti-CTLA-4 (16% versus 33%, p = 0.12), anti-PD-1 + anti-CTLA-4 (67% versus 56%, p = 0.34) and BRAF/MEK-inhibition (14% versus 23%, p = 0.06). Following anti-CTLA-4 treatment, no AYAs experienced a grade 3–4 colitis, while 17% of the older adults did (p = 0.046). There was no difference in response to treatment between AYAs and older adults. The longer overall survival observed in AYAs (hazard ratio (HR) 0.7; 95% CI 0.6–0.8) was explained by the increased cumulative incidence of non-melanoma related deaths in older adults (sub-distribution HR 2.8; 95% CI 1.5–4.9), calculated by competing risk analysis. The results of our national cohort study show that baseline characteristics and mutational profiles differ between AYAs and older adults with advanced melanoma, leading to different treatment choices made in daily practice. Once treatment is initiated, AYAs and older adults show similar tumor responses and melanoma-specific survival.

4 December 2019 in Cancers
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MSMaartje Schouwenburg
Maartje Schouwenburg
Karijn SuijkerbuijkKarijn Suijkerbuijk
Karijn Suijkerbuijk
RKRutger H.T. Koornstra
Rutger H.T. Koornstra
AJAnouk Jochems
Anouk Jochems
MZMichiel C.T. van Zeijl
Michiel C.T. van Zeijl
MWMichel Wouters
Michel Wouters
The prognosis of patients with advanced melanoma has improved dramatically. However, the clinical outcomes of patients with highly elevated serum lactate dehydrogenase (LDH) remain very poor. The aim of this study was to explore whether patients with normalized LDH after targeted therapy could benefit from subsequent treatment with immune checkpoint inhibitors (ICI). Data from all patients with BRAF-mutant metastatic melanoma with a highly elevated serum LDH at baseline (≥2× upper limit of normal) receiving first-line targeted therapy between 2012 and 2019 in the Netherlands were collected. Patients were stratified according to response status to targeted therapy and change in LDH at start of subsequent treatment with ICI. Differences in overall survival (OS) between the subgroups were compared using log-rank tests. After a median follow-up of 35.1 months, median OS of the total study population (n = 360) was 4.9 months (95% CI 4.4–5.4). Of all patients receiving subsequent treatment with ICI (n = 113), survival from start of subsequent treatment was significantly longer in patients who had normalized LDH and were still responding to targeted therapy compared to those with LDH that remained elevated (median OS 24.7 vs. 1.1 months). Our study suggests that introducing ICI upon response to targeted therapy with normalization of LDH could be an effective strategy in obtaining long-term survival in advanced melanoma patients with initial highly elevated serum LDH.

4 March 2019 in Annals of Surgical Oncology
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MBMartine Bloemendal
Martine Bloemendal
WWWouter W. van Willigen
Wouter W. van Willigen
KBKalijn Bol
Kalijn Bol
MBMarye Boers-Sonderen
Marye Boers-Sonderen
JBJohannes J. Bonenkamp
Johannes J. Bonenkamp
JWJohannes H. W. de Wilt
Johannes H. W. de Wilt
Purpose To evaluate the results of restaging completely resected stage IIIB/C melanoma prior to start of adjuvant therapy.

15 November 2016 in Drugs in R&D
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LLLaura W. Leicher
Laura W. Leicher
JGJacques C. de Graaf
Jacques C. de Graaf
WCWilko Coers
Wilko Coers
MTMetin Tascilar
Metin Tascilar
Jan Willem B. De GrootJan Willem B. De Groot
Jan Willem B. De Groot
Background Capecitabine monotherapy is a treatment option for selected patients with metastatic colorectal cancer (mCRC) and is administered to up to 17% of patients. Data are limited with regard to adverse events and dosing practices associated with capecitabine monotherapy in real-world situations. Objectives The aim of this study was to provide real-world data on adverse event rates and dose adjustments/discontinuations associated with capecitabine monotherapy in patients with mCRC. Methods This retrospective study analyzed data from CRC patients scheduled to receive up to eight planned cycles of capecitabine monotherapy between 2009 and 2013 at a single large community hospital in The Netherlands. Data on adverse events (hand-foot syndrome [HFS], gastrointestinal (GI) events, hematological adverse events, and cardiotoxicity), as well as relative dose intensities (RDIs), dose reductions, and discontinuations, were evaluated. Results Data from 86 patients (45 females; mean age at the start of treatment, 69 years) were included. A total of 46.5% of patients experienced HFS and 44.2% experienced a GI event at some time during treatment. Hematological events and cardiotoxicity were rare. Most patients (77%) started at below the recommended dose, and patients at the lowest dose also had the lowest median RDIs. Dose reductions and discontinuations occurred in 15–25% of patients who experienced HFS or GI event over the course of eight cycles. Conclusions HFS and GI events were very common in patients treated with capecitabine monotherapy in a real-world clinical setting. Most patients started treatment at below the recommended dose, and 15–25% of patients who had HFS or a GI event had a dose reduction or discontinuation.