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Molecular Pathology: Jelle Wesseling


Jelle Wesseling, M.D. Ph.D.Groupleader

About Jelle Wesseling

Research interest: Breast Cancer Biomarkers

Breast cancer is a heterogeneous disease ranging from being non-hazardous to life threatening. Accurate pathological and molecular analyses are key to make accurate predictions regarding prognosis and response to treatment. Therefore, we aim to find, validate, and implement biomarkers to make more precise and personalized predictions regarding prognosis and response to treatment.

Finding the balance between over- and undertreatment of breast Ductal Carcinoma In Situ (DCIS)

We try to find the balance between overdiagnosis and undertreatment of low-risk Ductal Carcinoma in Situ (DCIS). The rise in DCIS incidence due to screening has not resulted in a decrease of breast cancer related mortality. This implies that part of the DCIS lesions detected by population-based screening can be considered as overdiagnosis, putting many women at risk of overtreatment. Therefore, more accurate discrimination of low- vs. high-risk DCIS lesions is warranted. We aim to identify subsets of DCIS patients with a very low risk of developing an invasive ipsilateral breast cancer (BC) to define possible alternative treatment strategies for this subgroup of very low risk DCIS tumors, such as a wait and see policy.
 Retrospectively, we are performing both epidemiological and molecular pathology studies on a population-based cohort of 10,090 women treated for DCIS, with long time follow-up available. Prospectively, we initiated a randomized controlled, trial to evaluate the safety of active surveillance in 1240 women with LOw-Risk DCIS (LORD). This trial is coordinated by the BOOG and EORTC.

Development of clinically useful molecular tests to predict chemotherapy response of primary breast cancers

Within the neoadjuvant chemotherapy program, we aim to develop tests predicting response to preoperative chemotherapy. Since 2004 we collect pre-treatment biopsy material from all patients scheduled to receive neoadjuvant chemotherapy in the NKI-AVL. In addition, we precisely collect all clinical and pathological data of the patients, resulting in a database with over 1,400 patients registered, and from most of them biopsies for translational research are available, as well as resection specimens in case of remaining disease at surgery. In the past years we made significant progress in our search for biomarkers. Highlights are the association between a BRCA-like genomic profile and a remarkably better response to high dose chemotherapy. To assess this BRCA-like genomic profile in routine diagnostics we developed an easy to perform MLPA assay (collaboration with Petra Nederlof). We now started to compare somatic mutations, copy number alterations and gene expression levels between 'before' and 'after' chemotherapy samples from the same patient, to study the effect of chemotherapy on breast tumors and to identify potential resistance mechanisms.
Within this research line we collaborate intensively with the computational biology group of Lodewyk Wessels and with the medical oncology department (Sjoerd Rodenhuis, Gabe Sonke).

Furthermore, we are collaborating with Paula Elkhuizen, Astrid Scholten, Marc van de Vijver, and Harry Bartelink to find biomarkers determining breast cancer radiosensitivity.

The research of the Wesseling group is supported by grants from the Dutch Cancer Society/Alpe d'Huez, Pink Ribbon, A Sister's Hope and NWO-ZonMw.


Alaeikhanehshir, Sena

Sena Alaeikhanehshir

Ph.D. Student


In July 2017, I finished my last medical internship at the Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital at the Department of Surgery and received my MD from the University of Amsterdam - Academic Medical Centre (UVA-AMC). During this internship, I came to know dr. Wesseling as the lead investigator and study coordinator of the LORD trial. This trial aims to test whether active surveillance of screen-detected low-grade DCIS, a commonly found lesion considered as a potential precursor of breast cancer, is as safe as conventional treatment. I was selected as MD PhD student focusing on further initiation, implementation and analysis of the trial.

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Almekinders, Mathilde

Mathilde Almekinders, MD, MSc

Ph.D. Student and pathologist


In 2010 I obtained my medical degree and master of Biomedical Sciences at Leiden University. I completed my training as a pathologist in 2015 at Leiden University Medical center (LUMC).

Currently I work as a PhD student in the group of Jelle Wesseling and as a pathologist at the department of Pathology. My research focuses on the immune microenvironment of ductal carcinoma in situ (DCIS) aiming at the identification of biomarkers that can predict the biological behavior of DCIS in order to optimize individualized diagnosis and treatment.  

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Sophie Bosma

MD, Ph.D. Student


My name is Sophie Bosma. I graduated from medical school in 2012. Currently, I am a PhD student radiotherapy. After 2 years of fulltime research, I will combine my work as a graduate student with a residency in radiation oncology.
The main subject of my research is radiosensitivity and local recurrences in breast cancer. I will work on the 'PAPBI trial' and the 'Young boost trial' among other projects.



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Elshof, Lotte.jpg

Lotte Elshof, M.D.

Ph.D. Student


Since March 2012, I have been working at the NKI-AVL starting as a doctor on the surgical ward and as Ph.D. student. My research is focused on finding the balance between overdiagnosis and undertreatment of Ductal Carcinoma in Situ of the breast.





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Fu, Li-Ping

Li-Ping Fu

Research assistant


In 2011, I achieved my bachelor's degree in Molecular Biology (Hogeschool Utrecht), in 2016, I graduated from the Free University Amsterdam and obtained my master's degree in Health Sciences. During my studies, I gained experience while doing my internships in multiple labs, i.e. at the Academic Medical Center, the Netherlands Cancer Institute and the Free University Medical Center.

I worked on various projects regarding Alzheimer's disease, tuberculosis and Down syndrome. By combining my expertise and knowledge from both studies, I will be active as a Data Manager/ Research Assistant in the group of Jelle Wesseling assisting in the PRECISION (PREvent ductal Carcinoma In Situ Invasive Overtreatment Now) Initiative as funded by the Cancer Research UK Grand Challenge Award.


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Lips, Esther.JPG

Esther H. Lips, Ph.D.

Associate Staff Scientist


As a staff scientist in the Wesseling group my main focus is on developing prognostic and predictive tests for breast cancer. First, I am involved in finding biomarkers for neoadjuvant chemotherapy sensitivity. Second, I am involved in our translational DCIS research, where we aim to find and implement biomarkers for DCIS risk stratification. Third, I am developing  and implementing next generation sequencing techniques for diagnostic purposes.




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Maaken, Michiel de.jpg

Michiel de Maaker, Ing.



In august 2012, I started as technician on the Young Boost trial.
The main objective of the trial is to compare the effect of a high boost dose (26 Gy) with a low boost dose (16 Gy) in breast conserving therapy, on the local recurrence rate.
 Additional objectives are:
To test the genotypic and phenotypic profiles of breast tumors in young patients with invasive breast cancer, and its relation to:
a. Local recurrence after breast conserving treatment
b. Lymph node metastases
c. Distant metastases and survival
d. Radio sensitivity
e. Age

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Mulder, Lennart.jpg

Lennart Mulder, BASc



I studied Biology and Medical Laboratory Research at the University of Applied Sciences Leiden, where I obtained a bachelor's degree in Molecular Biology Cum Laude. Since 2006, I am employed as a research technician at the Netherlands Cancer Institute. Currently, I am involved in several clinical trials focused on preoperative chemotherapy for patients with breast cancer. The main goal of these trials is to develop molecular based tests to predict chemotherapy response in these patients.



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Nederlof, Iris

Iris Nederlof

Ph.D. Student


In October 2017 I graduated from medical school and
biomedical sciences at the Leiden University. Currently, I am a PhD student at
the division of molecular pathology. My research focuses on genetic properties
of breast carcinomas and the associations with cancer-immune interactions. I
will work on the 'TONIC trial', 'BASIS cohort' and the 'Young boost trial'
among other projects.

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Somer-Kristel, Petra.jpg

Petra Kristel, Ing.



I finished my technician education at the Amsterdam Univeristy of Applied Sciences in 1991. My first job was at the Academic Medical Center for 3 years. In 1994, I started working at the Netherlands Cancer Institute, eventually at the Molecular Pathology department. The main topic of our group is breast cancer. Since 2007 I am working for Jelle Wesseling. I always enjoyed working on several projects with PhD students, post-docs and others technicians.



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Van Ramshorst, Mette

Mette van Ramshorst, M.D.

Ph.D. Student


After graduating from medical school in 2012, I was a resident for one year at the medical oncology department of the Netherlands Cancer Institute. In March 2013, I started as a PhD student at the medical oncology/molecular pathology department. The coming years I will focus on optimizing neoadjuvant systemic treatment in HER2-positive breast cancer. Finding predictive biomarkers for response to neoadjuvant systemic treatment is one of the aims of my research.




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van Seijen, Maartje

Maartje van Seijen

Ph.D. student


In 2012 I achieved my medical degree and for two years I worked as a medical doctor at the emergency room and at the surgical department. In 2014 I started my traineeship to become a pathologist. Since July 2017 I temporarily quite the traineeship for three years to focus on research. During this Ph.D. I will mainly be involved in studying DCIS in the Precision project. I will compare clinical, histological and molecular characteristics of different international retrospective DCIS cohorts with the ultimate goal to build a stratification model that distinguish harmless DCIS from the potentially hazardous ones.

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Stoffers, Saskia

Saskia Stoffers



I obtained my bachelor's degree in Biomedical Sciences
and my master's degree in Neuroscience at the Free University (VU) in Amsterdam.
During my studies I have completed several internships at the Leiden University
Medical Center as well as at the Academic Medical Center and VU Medical Center.
I graduated in 2017 and will be working as a technican on the PRECISION
(PREvent ductal Carcinoma In Situ Invasive Overtreatment Now) project in Jelle
Wesseling's group.

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Visser, Lindy

Lindy L. Visser, MSc.

Ph.D. Student


August 2013, I achieved a master degree in Oncology at VU University Amsterdam. Today, I'm a PhD student studying ductal carcinoma in situ (DCIS) of the breast. Population-based breast cancer screening and implementation of digital mammography has resulted in an increased incidence of DCIS, but not in a decreased incidence of advanced breast cancer, suggesting overtreatment of DCIS lesions. Within this study I'm aiming to find biomarkers to distinguish harmless from aggressive lesions. Subsequently, these accurate biomarkers may aid to decide which woman should be treated and which one not, which creates the potential of sparing these patients intensive treatment.


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Key publications View All Publications

  • Next generation sequencing of triple negative breast cancer to find predictors for chemotherapy response

    (2015) Breast Cancer Res. Oct 3;17(1):134. doi: 10.1186/s13058-015-0642-8.

    Lips EH, Michaut M, Hoogstraat M, Mulder L, Besselink NJ, Koudijs MJ, Cuppen E, Voest EE, Bernards R, Nederlof PM, Wesseling J, Rodenhuis et al.

    Link to PubMed
  • Feasibility of a prospective, randomised, open-label, international multicentre, phase III, non-inferiority trial to assess the safety of active surveillance for low risk ductal carcinoma in situ - The LORD study

    (2015) Eur J Cancer. Aug;51(12):1497-510. doi: 10.1016/j.ejca.2015.05.008. Epub 2015 May 26.

    Elshof LE, Tryfonidis K, Slaets L, van Leeuwen-Stok AE, Skinner VP, Dif N, Pijnappel RM, Bijker N, Rutgers EJ, Wesseling J.

    Link to PubMed

Recent publications View All Publications

  • Insertional mutagenesis identifies drivers of a novel oncogenic pathway in invasive lobular breast carcinoma

    (2017) Nat Genet. Aug;49(8):1219-1230. doi: 10.1038/ng.3905. Epub 2017 Jun 26.

    Kas SM, de Ruiter JR, Schipper K, Annunziato S, Schut E, Klarenbeek S, Drenth AP, van der Burg E, Klijn C, Ten Hoeve JJ, Adams DJ, Koudijs...

    Link to PubMed
  • Breast Cancer Survival of BRCA1/BRCA2 Mutation Carriers in a Hospital-Based Cohort of Young Women

    (2017) J Natl Cancer Inst. Aug 1;109(8). doi: 10.1093/jnci/djw329

    Schmidt MK, van den Broek AJ, Tollenaar RA, Smit VT, Westenend PJ, Brinkhuis M, Oosterhuis WJ, Wesseling J, Janssen-Heijnen ML, Jobsen...

    Link to PubMed


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    Suzanne Romijn

  • E-mail

  • Telephone Number

    +31 20 512 9168



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