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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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Belt, Sandra van den

Sandra van den Belt

Postdoctoral Fellow


I have been working at PSOE since 1988 (and still do for 4 hours/week). My current position is epidemiologist.

The past 2 years I have worked as a data consultant at PALGA's. The subject of my PhD research was late effects of treatment for testicular cancer and Hodgkin's lymphoma. As a postdoc I coordinated the nationwide OMEGA cohort study to investigate the long-term risk of hormone-related cancers. I also coordinated BBMRI projects, to collect tumour blocks and a validation study regarding the use of encrypted BSN for record linkages between cohorts or biobanks and the Netherlands Cancer Registry and PALGA.

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Bhattacharjee, Proteeti

Proteeti Bhattacharjee

Scientific Project Manager


I completed B.Sc. in Biochemistry from University of Delhi and M.Sc. in Molecular and Human Genetics from Banaras Hindu University, Varanasi, India. In 2012, I received my PhD jointly from European Molecular Biology Laboratory (EMBL), Heidelberg and University of Heidelberg, Germany.
After a brief stint of post-doctoral work at EMBL, I moved into the field of science communication and management and worked at the Office of Information and Public Affairs (OIPA) in EMBL, Heidelberg.
Later, I joined Max Planck Gesellschaft (MPG), at the division of international relations in Munich where I managed the India country portfolio based in New Delhi at the German House for Research and Innovation. I obtained a micro-masters (edX) in International Business Management from Thunderbird
School of Global Management before joining NKI in September 2018 as Scientific Project Manager for PRECISION and B-CAST projects.

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Borden, Carolien van der

Carolien van der Borden

Ph.D. Student


In June 2018 I achieved a Master's degree in Oncology from the VU Amsterdam. During my Master's degree I worked for 5 months in the department of Neurosurgery at the Cancer Center Amsterdam and performed a six-month internship in the group of Laura van 't Veer at UC San Francisco, where I identified a unique set of hyper-activated kinases in chemo-resistant TNBC cell lines. Currently, I am a PhD student in the group of Jelle Wesseling. My research project is mainly focused on developing an immunological approach to intercept the progression of BRCA1-associated pre-invasive to invasive
breast cancer.

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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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Kreeft, Richard

Richard Kreeft



I graduated from Hogeschool Drenthe in Emmen in July 2007, earning my bachelor's degree in Life Sciences. During my studies, I completed an internship at the RIZA in Lelystad.

Before joining the NKI, I worked for 11 years at Agendia NV as a Diagnostic Technician, performing all the steps in the Mammaprint diagnostic breast cancer test. I also followed additional courses for performing internal audits, and supported the American branch of Agendia 3 times.

As a technician, I will work on the DCIS research theme in the Wesseling group.

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Liefaard, Marte

Marte Liefaard

Ph.D. Student


After completing medical school and a MSc in clinical epidemiology, I worked for 1.5 years as a doctor in internal medicine, first in the Hague and later at the NKI. 

In my current position as PhD student I am focused on blood-based screening methods for breast cancer, as well as identification of biomarkers that could aid in predicting response to treatment with pertuzumab for breast cancer.

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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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Liu, Yat-Hee

Yat-Hee Liu

Data Manager


I obtained a master's degree in Health Sciences at the VU University in Amsterdam and acquired experience in cancer research from having previously worked at the division of Psychosocial Research and Epidemiology at the NKI, and on clinical trials at the VUmc in Amsterdam and the Princess Maxima Center in Utrecht.

In January 2020 I started as datamanager for the PRECISION (PREvent ductal Carcinoma In Situ Invasive Overtreatment Now) project in the group of Jelle Wesseling.

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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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Schmitz, Renée

Renée Schmitz

Ph.D. Student


In July 2019, I graduated at Maastricht University Medical School. Throughout my masters, I worked on research regarding end of life care in breast cancer patients at the department of Medical Oncology at the Maastricht University Medical Hospital. 

September 2019, I started working at the NKI as an MD PhD student in the group of Jelle Wesseling. My work focusses on retrospective, epidemiological studies regarding ductal carcinoma in situ (DCIS) within the PRECISION project, aiming to develop a risk stratification model for DCIS. Secondly, I am one of the study coordinators of the LORD trial, a randomized controlled trial to evaluate the safety of active surveillance in women with LOw-Risk DCIS.

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Sobral-Leite, Marcelo

Marcelo Sobral-Leite

Postdoctoral fellow


I work on the PRECISION project to integrate clinical, pathological, imaging and molecular data from DCIS cohorts. The aim is to develop a risk prediction model to reduce the over-treatment of DCIS.

In 2013, I joined Schmidt's group at NKI, where I applied  molecular pathology approaches to develop biomarkers of breast cancer outcome. I obtained my PhD at Utrecht University in 2019.

I am an oncology pharmacist with master's in pharmacology by the Federal University of Rio de Janeiro. I have long standing interest in precision medicine research, since I joined the Brazilian Cancer Institute in 2009.

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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 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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Key publications View All Publications

  • Ductal carcinoma in situ: to treat or not to treat, that is the question

    (2019) Br J Cancer. Aug;121(4):285-292. doi: 10.1038/s41416-019-0478-6. Epub 2019 Jul 9. Review.

    van Seijen M, Lips EH, Thompson AM, Nik-Zainal S, Futreal A, Hwang ES, Verschuur E, Lane J, Jonkers J, Rea DW, Wesseling J; PRECISION team

    Link to PubMed
  • Discordant Marker Expression Between Invasive Breast Carcinoma and Corresponding Synchronous and Preceding DCIS

    (2019) Am J Surg Pathol. Jun 14. doi: 10.1097/PAS.0000000000001306.

    Visser LL, Elshof LE, Van de Vijver K, Groen EJ, Almekinders MM, Sanders J, Bierman C, Peters D, Hofland I, Broeks A, van Leeuwen FE, Rutgers EJT, Schmidt MK, Schaapveld M, Lips EH, Wesseling J.

    Link to PubMed

Recent publications View All Publications

  • Are contralateral parenchymal enhancement on dynamic contrast-enhanced MRI and genomic ER-pathway activity in ER-positive/HER2-negative breast cancer related?

    (2019) Eur J Radiol. Dec;121:108705. doi: 10.1016/j.ejrad.2019.108705. Epub 2019 Oct 16.

    van der Velden BHM, Bismeijer T, Canisius S, Loo CE, Lips EH, Wesseling J, Viergever MA, Wessels LFA, Gilhuijs KGA.

    Link to PubMed
  • Reliability of preoperative breast biopsies showing ductal carcinoma in situ and implications for non-operative treatment: a cohort study

    (2019) Breast Cancer Res Treat. Nov;178(2):409-418. doi: 10.1007/s10549-019-05362-1.

    Mannu GS, Groen EJ, Wang Z, Schaapveld M, Lips EH, Chung M, Joore I, van Leeuwen FE, Teertstra HJ, Winter-Warnars GAO, Darby SC, Wesseling J.

    Link to PubMed


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    Suzanne Romijn

  • E-mail

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    +31 20 512 9168



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