Search

To prevent duodenal and ampullary cancer in familial adenomatous polyposis (FAP) patients, a diagnosis of high grade dysplasia (HGD) plays an important role in the clinical management. Previous research showed that FAP patients are both over- and undertreated after a misdiagnosis of HGD, indicating unwarranted variation. We aimed to investigate the laboratory variation in dysplasia grading of duodenal adenomas and explore possible explanations for this variation. We included data from all Dutch pathology laboratories between 1991 and 2020 by retrieving histology reports from upper endoscopy specimens of FAP patients from the Dutch nationwide pathology databank (PALGA). Laboratory variation was investigated by comparing standardized proportions of HGD. To describe the degree of variation between the laboratories a factor score was calculated. A funnel plot was used to identify outliers. A total of 3050 specimens from 25 laboratories were included in the final analyses. The mean observed HGD proportion was 9.4%. The top three HGD-diagnosing laboratories diagnosed HGD 3.9 times more often than the lowest three laboratories, even after correcting for case-mix. No outliers were identified. Moderate laboratory variation was found in HGD diagnoses of duodenal tissue of FAP patients after adjusting for case-mix. Despite the fact that no outliers were observed, there may well be room for quality improvement. Concentration of these patients in expertise centers may decrease variation. To further reduce unwarranted variation, we recommend (inter)national guidelines to become more uniform in their recommendations regarding duodenal tissue sampling and consequences of HGD diagnoses. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Most people who are at increased familial colorectal cancer (FCRC) risk are not identified, despite the need for enhanced surveillance colonoscopy for effective CRC prevention. An online self‐test may enhance this identification. We assessed whether taking an online self‐test to identify increased FCRC risk increases anxiety, distress or CRC risk perception in population‐based CRC screening. Method: After the precolonoscopy consultation, patients who had a positive immunohistochemical occult faecal blood test (iFOBT+) in population‐based CRC screening were invited by email to take an online self‐test at home which returned details of family history. Anxiety (STAI‐DY), distress (HADS) and CRC risk perception were assessed immediately before and after taking the online self‐test and 2 weeks later. Results: Of 250 participants invited, 177 (71%) completed the online self‐test and psychological questionnaires and 153 (61%) completed questionnaires 2 weeks later. The median age was 65 years (range 61–75). The FCRC risk was increased in 17 participants (9.6%). Of these, 12 (6.8%) had a highly increased FCRC risk and may benefit from germline genetic testing for Lynch syndrome. In 7 of 17 participants (40%) the self‐test obtained novel information on family history. Anxiety and distress levels were, and remained, below a clinically relevant level. Perception of CRC risk remained unchanged. Most participants (83%) would recommend the online self‐test to others. Conclusion: Of those with a iFOBT+, 9.6% had a previously unidentified increasedFCRC risk and require an enhanced surveillance colonoscopy instead of iFOBT. As screening for this risk did not increase anxiety or distress, and was highly acceptable, we recommend adding the online self‐test to population‐based CRC screening. [ABSTRACT FROM AUTHOR]

Background and study aims: The clinical utility of narrow-band imaging (NBI) for Barrett's esophagus is limited by the multiplicity of classification schemes. We evaluated the interobserver agreement and accuracy of a new consensus-driven simplified binary classification of NBI surface patterns. Patients and methods: NBI images from macroscopically normal areas in patients with Barrett's esophagus were retrieved from endoscopy databases and were randomized for review by seven endoscopists (three experts, four nonexperts). A simplified binary classification of NBI mucosal and vascular patterns was used: (1) regular pattern (nondysplastic Barrett's esophagus); (2) irregular pattern (dysplastic Barrett's esophagus). Agreement in relation to surface patterns and predicted histology (dysplasia vs. no dysplasia) was calculated using κ statistics. Results: A total of 252 NBI images from 75 patients with Barrett's esophagus were assessed: 93 showed intestinal metaplasia, 91 low-grade dysplasia, and 68 high-grade dysplasia/esophageal adenocarcinoma. The median score for image quality was 4 (very good). Interobserver agreement for mucosal and vascular patterns and dysplasia prediction was fair: κ = 0.40 (95%CI: 0.37-0.42), 0.36 (95%CI: 0.33-0.38), and 0.39 (95%CI: 0.36-0.41) respectively, with comparable results for experts and nonexperts. Intraobserver agreement was substantially better among experts than among nonexperts, with mucosal κ = 0.63 vs. 0.49, vascular κ = 0.58 vs. 0.43, and predicted histology κ = 0.68 vs. 0.54 (all P < 0.005). Mean sensitivity and specificity of NBI surface patterns for predicting dysplasia were 47% (95%CI: 44%-55%) and 72% (95%CI: 69%-76%) respectively. Conclusions: Using a consensus-driven simplified classification of NBI surface patterns for Barrett's esophagus, the interobserver agreement was fair with suboptimal sensitivity and specificity. Significant improvements in NBI interpretation are needed prior to the routine use of NBI surface patterns for the assessment of Barrett's esophagus. [ABSTRACT FROM AUTHOR]

This review deals with the current, well-established indications for two-( 18 F)-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scanning in patients with gastrointestinal cancers. FDG-PET is a non-invasive, functional imaging technique. FDG exploits the native glucose transporter to enter the cell. Since many tumours have enhanced glucose uptake, FDG is readily accumulated in malignant cells and can be detected by a PET camera. FDG-PET has been established as an important diagnostic tool in clinical oncology. This review deals with the current, well-established indications for FDG-PET scanning in patients with gastrointestinal cancers. In the current practice, FDG-PET is most commonly used to stage oesophageal carcinoma, to detect and stage recurrence of colorectal carcinoma and to differentiate between benign and malignant pancreatic lesions. The benefit of FDG-PET scanning in patients with oesophagus carcinoma is best established in stage IV disease, as the diagnostic accuracy to detect metastatic disease is higher compared to the combination of computed tomography (CT) and endoscopic ultrasound (EUS). In patients with a history of colorectal carcinoma, FDG-PET scanning is particularly effective in diagnosing recurrent disease, especially in those with a rising carcinoembryonic antigen without a suspect lesion on conventional imaging. Large series have indicated that the sensitivity and specificity for detecting recurrent colorectal carcinoma are in the range of 87%-100% and 66%-100%, respectively. Equally, FDG-PET has a high sensitivity (68%-96%) and specificity (78%-100%) in detecting pancreatic carcinoma in patients with a suspicious-looking pancreatic mass on CT scan. Lastly, we focus on the use of FDG-PET as a modality for early monitoring of treatment response in patients with gastrointestinal stromal cell tumours. Without doubt, future developments will further establish the diagnostic role of the FDG-PET scan in the care of patients with gastrointestinal cancers. [ABSTRACT FROM AUTHOR]

We report the experimental demonstration of single-photon and cascaded photon pair emission in the infrared, originating from a single InAsP quantum dot embedded in a standing InP nanowire. A regular array of nanowires is fabricated by epitaxial growth on an electron-beam patterned substrate. Photoluminescence spectra taken on single quantum dots show narrow emission lines. Superconducting single photon detectors, which have a higher sensitivity than avalanche photodiodes in the infrared, enable us to measure auto and cross correlations. Clear antibunching is observed [g(2)(0)=0.12] and we show a biexciton-exciton cascade, which can be used to create entangled photon pairs. [ABSTRACT FROM AUTHOR]

We report InP nanowire photodetectors with a single InAsP quantum dot as light absorbing element. With excitation above the InP band gap, the nanowire photodetectors are efficient (quantum efficiency of 4%). Under resonant excitation of the quantum dot, the photocurrent amplitude depends on the linear polarization direction of the incident light. The photocurrent is enhanced (suppressed) for a polarization parallel (perpendicular) to the axis of the nanowire (contrast 0.83). The active detection volume under resonant excitation is 7×103 nm3. These results show the promising features of quantum dots embedded in nanowire devices for electrical light detection at high spatial resolution. [ABSTRACT FROM AUTHOR]

We report voltage dependent photoluminescence experiments on single indium arsenide phosphide (InAsP) quantum dots embedded in vertical surround-gated indium phosphide (InP) nanowires. We show that by tuning the gate voltage, we can access different quantum dot charge states. We study the anisotropic exchange splitting by polarization analysis, and identify the neutral and singly charged exciton. These results are important for spin addressability in a charge tunable nanowire quantum dot. [ABSTRACT FROM AUTHOR]