Publications by authors named "Gerrit-A Meijer"

Circulating cell-free DNA (cfDNA) assays for monitoring individuals with cancer typically rely on prior identification of tumor-specific mutations. Here, we develop a tumor-independent and mutation-independent approach (DELFI-tumor fraction, DELFI-TF) using low-coverage whole genome sequencing to determine the cfDNA tumor fraction and validate the method in two independent cohorts of patients with colorectal or lung cancer. DELFI-TF scores strongly correlate with circulating tumor DNA levels (ctDNA) (r = 0.

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  • * A study analyzed 200 individuals with Lynch syndrome to assess the effectiveness of faecal VOCs, both alone and in combination with FIT, in identifying relevant colorectal neoplasia before and after colonoscopy.
  • * Results indicated high sensitivity and negative predictive values for detecting colorectal cancer and advanced adenomas using VOC analysis, suggesting that faecal VOCs could guide optimal colonoscopy intervals and improve patient monitoring following polypectomy.
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Ovarian cancer is a leading cause of death for women worldwide in part due to ineffective screening methods. In this study, we used whole-genome cell-free DNA (cfDNA) fragmentome and protein biomarker (CA-125 and HE4) analyses to evaluate 591 women with ovarian cancer, benign adnexal masses, or without ovarian lesions. Using a machine learning model with the combined features, we detected ovarian cancer with specificity >99% and sensitivity of 72%, 69%, 87%, and 100% for stages I-IV, respectively.

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Structural variants (SVs) caused by chromosomal rearrangements in common fragile sites or long interspersed nuclear element (LINE) retrotranspositions are highly prevalent in colorectal cancer. However, methodology for the targeted detection of these SVs is lacking. This article reports the use of formalin-fixed, paraffin-embedded targeted-locus capture (FFPE-TLC) sequencing as a novel technology for the targeted detection of tumor-specific SVs.

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Motivation: Genomic instability is a hallmark of cancer, leading to many somatic alterations. Identifying which alterations have a system-wide impact is a challenging task. Nevertheless, this is an essential first step for prioritizing potential biomarkers.

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  • Colonoscopy surveillance for colorectal cancer (CRC) can be burdensome for patients, and stool tests might help reduce the need for colonoscopies by identifying individuals at higher risk.
  • This study involved 3453 participants aged 50-75 who completed multiple stool tests and colonoscopies to assess the accuracy of these methods for detecting advanced neoplasia.
  • Results indicated that stool-based strategies could effectively reduce colonoscopy frequency by 15%-41% while being safer and more cost-effective, particularly with fecal immunochemical tests (FITs), although multitarget stool DNA testing was found to be more expensive.
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  • The study evaluates strategies for colorectal cancer (CRC) surveillance in individuals with familial CRC risk, comparing different methods of colonoscopy and fecal testing.
  • The optimal strategy identified is a combination of 10-yearly colonoscopy and 2-yearly FIT from ages 40 to 80, which enhances life quality and reduces costs.
  • This approach not only prevents more CRC deaths but also significantly decreases the number of colonoscopies required compared to current guidelines.
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Background: Current patient selection for adjuvant chemotherapy (ACT) after curative surgery for stage II colon cancer (CC) is suboptimal, causing overtreatment of high-risk patients and undertreatment of low-risk patients. Postoperative circulating tumor DNA (ctDNA) could improve patient selection for ACT.

Objectives: We conducted an early model-based evaluation of the (cost-)effectiveness of ctDNA-guided selection for ACT in stage II CC in the Netherlands to assess the conditions for cost-effective implementation.

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  • Colonoscopy surveillance for individuals with Lynch syndrome is challenging, and colorectal cancers can still occur despite regular screenings.
  • A study evaluated the efficacy of fecal immunochemical tests (FIT) to determine the best intervals for colonoscopy by measuring specific thresholds of hemoglobin in stool samples.
  • Results indicated that using a lower FIT threshold (2.5 μg Hb/g) increased the detection rate of relevant neoplasia, with even better specificity seen at a threshold of 4.1 μg Hb/g, suggesting that FIT could potentially allow many Lynch syndrome patients to delay unnecessary colonoscopies while still effectively identifying those at risk for advanced neoplasia.
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Background: The efficacy of PD-1 blocking agents in advanced NSCLC has shown prolonged effectiveness, but only in a minority of patients. Multiple biomarkers have been explored to predict treatment benefit, yet their combined performance remains inadequately examined. In this study, we assessed the combined predictive performance of multiple biomarkers in NSCLC patients treated with nivolumab.

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Environmental factors like the pathogenicity island polyketide synthase positive (pks+) Escherichia coli (E. coli) could have potential for risk stratification in colorectal cancer (CRC) screening. The association between pks+ E.

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Up to 30% of colorectal cancers (CRCs) develop from sessile serrated lesions (SSLs). Within the serrated neoplasia pathway, at least two principally distinct oncogenetic routes exist generating microsatellite-stable and microsatellite-instable CRCs, respectively. Aberrant DNA methylation (DNAm) is found early in the serrated pathway and might play a role in both oncogenetic routes.

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Background: The faecal immunochemical test (FIT) is widely employed for colorectal cancer screening. However, its sensitivity for advanced precursor lesions remains suboptimal. The multitarget FIT (mtFIT), measuring haemoglobin, calprotectin, and serpin family F member 2, has demonstrated enhanced sensitivity for advanced neoplasia, especially advanced adenomas, at equal specificity to FIT.

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Background: Post-colonoscopy colorectal cancers (PCCRCs) decrease the effect of colorectal cancer (CRC) screening programs. To enable PCCRC incidence reduction in the long-term, we classified PCCRCs diagnosed after colonoscopies performed in a fecal immunochemical test (FIT)-based screening program.

Methods: PCCRCs diagnosed after colonoscopies performed between 2014-2016 for a positive FIT in the Dutch CRC screening program were included.

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  • Oncology is shifting towards genome-driven practices, but most cancer diagnostics still rely on traditional microscopy methods, creating delays in using new genomic biomarkers for patient treatment.* -
  • Whole-genome sequencing (WGS) can improve diagnostics by detecting numerous genomic changes in one cost-effective test, and it has been shown to be feasible and valid in a clinical setting, with results provided in about 11 workdays.* -
  • Successful WGS implementation, such as at the Netherlands Cancer Institute, requires a detailed protocol addressing sample handling and integration into clinical workflows to overcome challenges faced by pathology labs using conventional sample methods.*
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Purpose: Because PD-1 blockade is only effective in a minority of patients with advanced-stage non-small cell lung cancer (NSCLC), biomarkers are needed to guide treatment decisions. Tumor infiltration by PD-1T tumor-infiltrating lymphocytes (TIL), a dysfunctional TIL pool with tumor-reactive capacity, can be detected by digital quantitative IHC and has been established as a novel predictive biomarker in NSCLC. To facilitate translation of this biomarker to the clinic, we aimed to develop a robust RNA signature reflecting a tumor's PD-1T TIL status.

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Circulating tumor DNA (ctDNA) detection has multiple promising applications in oncology, but the road toward implementation in clinical practice is unclear. We aimed to support the implementation process by exploring potential future pathways of ctDNA testing. To do so, we studied four ctDNA-testing applications in two cancer types and elicited opinions from 30 ctDNA experts in the Netherlands.

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Purpose: Genome sequencing (GS) enables comprehensive molecular analysis of tumors and identification of hereditary cancer predisposition. According to guidelines, directly determining pathogenic germline variants (PGVs) requires pretest genetic counseling, which is cost-ineffective. Referral for genetic counseling based on tumor variants alone could miss relevant PGVs and/or result in unnecessary referrals.

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Unlabelled: Current morphologic features defining advanced adenomas (size ≥10 mm, high-grade dysplasia or ≥25% villous component) cannot optimally distinguish individuals at high risk or low risk of metachronous colorectal cancer (me-CRC), which may result in suboptimal surveillance. Certain DNA copy-number alterations (CNAs) are associated with adenoma-to-carcinoma progression. We aimed to evaluate whether these molecular features can better predict an individual's risk of me-CRC than the morphologic advanced adenoma features.

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Rapid advancements in the area of early cancer detection have brought us closer to achieving the goals of finding cancer early enough to treat or cure it, while avoiding harms of overdiagnosis. We evaluate progress in the development of early cancer detection tests in the context of the current principles for cancer screening. We review cell-free DNA (cfDNA)-based approaches using mutations, methylation, or fragmentomes for early cancer detection.

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  • Scientists are finding new ways to test for colorectal cancer that are easier and less invasive than traditional methods.
  • A group of experts updated the rules for how to evaluate these new tests to make sure they're effective.
  • The new tests should be compared to the existing reliable tests and go through several phases of research to ensure they're safe and useful in real-world situations.
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Purpose: Circulating tumor DNA (ctDNA) has the potential to guide therapy selection and monitor treatment response in patients with metastatic cancer. However, germline and clonal hematopoiesis-associated alterations can confound identification of tumor-specific mutations in cell-free DNA (cfDNA), often requiring additional sequencing of tumor tissue. The current study assessed whether ctDNA-based treatment response monitoring could be performed in a tumor tissue-independent manner by combining ultra-deep targeted sequencing analyses of cfDNA with patient-matched white blood cell (WBC)-derived DNA.

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Background: For optimizing fecal immunochemical test (FIT)-based screening programs, reducing the rate of missed colorectal cancers (CRCs) by FIT (FIT-interval CRCs) is an important aspect. Knowledge of the molecular make-up of these missed lesions could facilitate more accurate detection of all (precursor) lesions.

Aim: To compare the molecular make-up of FIT-interval CRCs to lesions that are detected by FIT [screen-detected CRCs (SD-CRCs)].

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Circulating tumor DNA (ctDNA) is a promising new biomarker with multiple potential applications in cancer care. Estimating total cost of ctDNA testing is necessary for reimbursement and implementation, but challenging because of variations in workflow. We aimed to develop a micro-costing framework for consistent cost calculation of ctDNA testing.

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Background: Clinically implemented prognostic biomarkers are lacking for the 80% of colorectal cancers (CRCs) that exhibit chromosomal instability (CIN). CIN is characterised by chromosome segregation errors and double-strand break repair defects that lead to somatic copy number aberrations (SCNAs) and chromosomal rearrangement-associated structural variants (SVs), respectively. We hypothesise that the number of SVs is a distinct feature of genomic instability and defined a new measure to quantify SVs: the tumour break load (TBL).

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