Publications by authors named "Niels Kok"

Objective: To compare nationwide outcomes of robotic liver resection (RLR) with laparoscopic liver resection (LLR).

Background: Minimally invasive liver resection is increasingly performed using the robotic approach as this could help overcome inherent technical limitations of laparoscopy. It is unknown if this translates to improved patient outcomes.

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Introduction: Clear guidelines for colorectal lung metastasis (LM) treatment are not available. This study aimed to provide insight into the treatment strategies and efficacy of local and systemic therapy in patients with LM eligible for (potentially) curative treatment.

Methods: This was a retrospective study of patients with ≤5 LM discussed in two tertiary referral centers.

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Article Synopsis
  • * Out of 3,530 patients, 11.6% required conversion, with robotic procedures having a lower conversion rate compared to laparoscopic ones, and conversion associated with various complications, like increased blood loss and longer hospital stays.
  • * Emergency conversions showed even more severe outcomes, such as significantly higher blood loss and increased rates of intensive care admissions compared to non-emergency cases.
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Rieske non-heme iron-dependent oxygenases (ROs) are a versatile group of enzymes traditionally associated with the degradation of aromatic xenobiotics. In addition, ROs have been found to play key roles in natural product biosynthesis, displaying a wide catalytic diversity with typically high regio- and stereo- selectivity. However, the detailed characterization of ROs presents formidable challenges due to their complex structural and functional properties, including their multi-component composition, cofactor dependence, and susceptibility to reactive oxygen species.

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Introduction: To improve care for patients with colorectal peritoneal metastases (CRC-PM) or pseudomyxoma peritonei (PMP), the Dutch CRS-HIPEC quality registry was initiated in 2019. The aims are to describe the development and content of this registry and to give insight into the data collected during the first years.

Materials And Methods: The registry is an observational cohort in the Netherlands.

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Article Synopsis
  • The study evaluated the prognostic significance of total tumor volume (TTV) in predicting early recurrence and overall survival in patients with colorectal liver metastases (CRLM) who received systemic therapy followed by local treatment.
  • Results showed that both baseline TTV and changes in TTV after treatment were significantly associated with early recurrence and overall survival, while conventional measures like RECIST1.1 did not show predictive value.
  • Findings were validated in an external patient cohort, confirming that TTV provides important prognostic information beyond traditional clinical factors for patients with initially unresectable CRLM.
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Background: Clinical auditing is a powerful tool to evaluate and improve healthcare. Deviations from the expected quality of care are identified by benchmarking the results of individual hospitals using national averages. This study aimed to evaluate the use of quality indicators for benchmarking hepato-pancreato-biliary (HPB) surgery and when outlier hospitals could be identified.

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Rieske non-heme iron oxygenases (ROs) are redox enzymes essential for microbial biodegradation and natural product synthesis. These enzymes utilize molecular oxygen for oxygenation reactions, making them very useful biocatalysts due to their broad reaction scope and high selectivities. The mechanism of oxygen activation in ROs involves electron transfers between redox centers of associated protein components, forming an electron transfer chain (ETC).

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The treatment landscape for patients with colon cancer is continuously evolving. Risk-adapted treatment strategies, including neoadjuvant chemotherapy and immunotherapy, are slowly finding their way into clinical practice and guidelines. Radiologists are pivotal in guiding clinicians toward the most optimal treatment for each colon cancer patient.

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Background: Hepatic arterial infusion pump chemotherapy combined with systemic chemotherapy (HAIP-SYS) for liver-only colorectal liver metastases (CRLMs) has shown promising results but has not been adopted worldwide. This study evaluated the feasibility of HAIP-SYS in the Netherlands.

Methods: This was a single-arm phase II study of patients with CRLMs who received HAIP-SYS consisting of floxuridine with concomitant systemic FOLFOX or FOLFIRI.

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Introduction: This study investigates the incidence of extrahepatic perfusion and incomplete hepatic perfusion at intraoperative methylene blue testing and on postoperative nuclear imaging in patients undergoing hepatic arterial infusion pump (HAIP) chemotherapy.

Methods: The first 150 consecutive patients who underwent pump implantation in the Netherlands were included. All patients underwent surgical pump implantation with the catheter in the gastroduodenal artery.

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Background: In 2013, the nationwide Dutch Hepato Biliary Audit (DHBA) was initiated. The aim of this study was to evaluate changes in indications for and outcomes of liver surgery in the last decade.

Methods: This nationwide study included all patients who underwent liver surgery for four indications, including colorectal liver metastases (CRLM), hepatocellular carcinoma (HCC), and intrahepatic- and perihilar cholangiocarcinoma (iCCA - pCCA) between 2014 and 2022.

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Purpose: Training and evaluation of the performance of a supervised deep-learning model for the segmentation of hepatic tumors from intraoperative US (iUS) images, with the purpose of improving the accuracy of tumor margin assessment during liver surgeries and the detection of lesions during colorectal surgeries.

Approach: In this retrospective study, a U-Net network was trained with the nnU-Net framework in different configurations for the segmentation of CRLM from iUS. The model was trained on B-mode intraoperative hepatic US images, hand-labeled by an expert clinician.

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Background: Approximately 70% of patients with colorectal liver metastases (CRLM) experiences intrahepatic recurrence after initial liver resection. This study assessed outcomes and hospital variation in repeat liver resections (R-LR).

Methods: This population-based study included all patients who underwent liver resection for CRLM between 2014 and 2022 in the Netherlands.

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Background: Before 2016, patients with isolated synchronous colorectal peritoneal metastases (PMCRC) diagnosed in expert centers had a higher odds of undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) and better overall survival (OS) than those diagnosed in referring centers. Nationwide efforts were initiated to increase awareness and improve referral networks.

Methods: This nationwide study aimed to evaluate whether the between-center differences in odds of undergoing CRS-HIPEC and OS have reduced since these national efforts were initiated.

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Background: Textbook outcome (TO) represents a multidimensional quality measurement, encompassing the desirable short-term outcomes following surgery. This study aimed to investigate whether achieving TO after resection of colorectal liver metastases (CRLM) surgery is related to better overall survival (OS) in a national cohort.

Method: Data was retrieved from the Dutch Hepato Biliary Audit.

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Aim: The aim was to explore how findings of whole-body MRI including diffusion-weighted imaging (DW-MRI) compared to the routine diagnostic workup with CT and/or F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in patients with suspected recurrent colorectal cancer (CRC).

Method: This was an exploratory retrospective analysis of 55 patients with a clinical suspicion of recurrent CRC who underwent DW-MRI following CT and/or FDG-PET/CT. Two readers in consensus interpreted all clinical imaging reports and converted each described lesion into a confidence score (1 = definitely benign to 5 = definitely malignant).

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Neuroendocrine neoplasms (NENs) comprise well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). Treatment options for patients with NENs are limited, in part due to lack of accurate models. We establish patient-derived tumor organoids (PDTOs) from pulmonary NETs and derive PDTOs from an understudied subtype of NEC, large cell neuroendocrine carcinoma (LCNEC), arising from multiple body sites.

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Background: Guidelines are inconclusive on whether contrast-enhanced MRI using gadoxetic acid and diffusion-weighted imaging should be added routinely to CT in the investigation of patients with colorectal liver metastases who are scheduled for curative liver resection or thermal ablation, or both. Although contrast-enhanced MRI is reportedly superior than contrast-enhanced CT in the detection and characterisation of colorectal liver metastases, its effect on clinical patient management is unknown. We aimed to assess the clinical effect of an additional liver contrast-enhanced MRI on local treatment plan in patients with colorectal liver metastases amenable to local treatment, based on contrast-enhanced CT.

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Introduction: Physical activity (PA) is associated with higher quality of life and probably better prognosis among colorectal cancer (CRC) patients. This study focuses on determinants of PA among CRC patients from diagnosis until 5 yr postdiagnosis.

Methods: Sociodemographic and disease-related factors of participants of two large CRC cohort studies were combined.

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Article Synopsis
  • The study examines treatment outcomes for asymptomatic patients with unresectable colorectal metastases who have untreated primary tumors, focusing on left-sided versus right-sided colon cancer.
  • Out of 523 patients with stage IV colon cancer, 221 started treatment specifically for metastases, revealing that 21% developed complications requiring invasive intervention, with left-sided tumors facing a higher complication rate (29%) compared to right-sided tumors (13%).
  • The findings suggest that left-sided primary tumors pose a greater risk for complications, indicating the need for careful monitoring and potential early surgical intervention for these patients.
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JCO Whether adjuvant hyperthermic intraperitoneal chemotherapy (HIPEC) might prevent peritoneal metastases after curative surgery for high-risk colon cancer is an ongoing debate. This study aimed to determine 5-year oncologic outcomes of the randomized multicenter COLOPEC trial, which included patients with clinical or pathologic T4N0-2M0 or perforated colon cancer and randomly assigned (1:1) to either adjuvant systemic chemotherapy and HIPEC (n = 100) or adjuvant systemic chemotherapy alone (n = 102). HIPEC was performed using a one-time administration of oxaliplatin (460 mg/m, 30 minutes, 42°C, concurrent fluorouracil/leucovorin intravenously), either simultaneously (9%) or within 5-8 weeks (91%) after primary tumor resection.

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Background: In colorectal liver metastases (CRLM) patients, combination of liver resection and ablation permit a more parenchymal-sparing approach. This study assessed trends in use of combined resection and ablation, outcomes, and overall survival (OS).

Methods: This population-based study included all CRLM patients who underwent liver resection between 2014 and 2022.

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