Petur Snaebjornsson

The chameleon of neuroinflammation: magnetic resonance imaging characteristics of natalizumab-associated progressive multifocal leukoencephalopathy:

Natalizumab is a monoclonal antibody against α4-integrin approved for the treatment of multiple sclerosis (MS) due to a positive effect on clinical and magnetic resonance imaging (MRI) outcome measures. However, one relatively rare but serious side effect of this drug is a higher risk of developing progressive multifocal leukoencephalopathy (PML). Since the FDA approval, more than 300 natalizumab-associated PML cases have been documented among more than 100,000 treated MS patients. MRI is a crucial tool in the surveillance of patients treated with natalizumab in order to detect possible signs of PML in the asymptomatic stage. Although classical imaging characteristics of PML are well established, MRI findings in natalizumab-associated PML, particularly in early disease stages, show rather new and heterogeneous imaging findings including different patterns of inflammation with contrast enhancement. This review provides a comprehensive overview of the heterogeneous imaging findings in natalizumab-associated PML in the context of the underlying pathophysiology, histopathology, and the diagnostic procedure. We describe the MRI patterns of PML lesion evolution and complications including immune reconstitution inflammatory syndrome (IRIS). Finally, we present guidelines to differentiate MRI findings in PML from inflammatory demyelinating lesions, to facilitate the early diagnosis of PML in patients treated with natalizumab.

pT4 stage II and III colon cancers carry the worst prognosis in a nationwide survival analysis. Shepherd's local peritoneal involvement revisited

The aim of this study is to clarify the prognostic importance of several well‐known but still debated pathological variables related to the survival of colon cancer patients. The study focuses on the definition and survival carried by the pT4 category and stage II where the presence of high‐risk variables may determine whether or not adjuvant chemotherapy is administered. A retrospective nationwide study was carried out including all colon cancer patients that underwent resection in Iceland between 1990 and 2004 (n = 889). All histopathology was reassessed. Cancer‐specific survival (CSS) and overall survival were analysed using Kaplan‐Meier and Cox regression analysis. In stage II, the five‐year CSS for pT4 was 50% (95% CI, 32–69%), which was the lowest survival observed in that stage. In stage III the five‐year CSS was 30% (95% CI, 18–41%) and 37% (95% CI, 26–48%) for pT4 and pN2 tumors, respectively. Lymphatic invasion and differentiation had no prognostic value in stage II. The survival associated with pT4a versus pT4b depends on how these categories are defined with regard to Shepherds local peritoneal involvement (LPI). In the present series, pT4 is a major indicator of poor prognosis in patients with stage II and III colon carcinoma. Four‐tiered TNM or Dukes staging systems are insufficient by not taking this variable into account. Only Shepherds LPI4 and a subgroup of LPI3 (i.e., borderline LPI3/LPI4) should qualify for the pT4a subcategory. The results do not support lymphatic invasion or poor differentiation as high‐risk stage II variables.

Prognostic value of BRAF and KRAS mutation status in stage II and III microsatellite instable colon cancers

Microsatellite instability (MSI) has been associated with favourable survival in early stage colorectal cancer (CRC) compared to microsatellite stable (MSS) CRC. The BRAF V600E mutation has been associated with worse survival in MSS CRC. This mutation occurs in 40% of MSI CRC and it is unclear whether it confers worse survival in this setting. The prognostic value of KRAS mutations in both MSS and MSI CRC remains unclear. We examined the effect of BRAF and KRAS mutations on survival in stage II and III MSI colon cancer patients. BRAF exon 15 and KRAS exon 2–3 mutation status was assessed in 143 stage II (n = 85) and III (n = 58) MSI colon cancers by high resolution melting analysis and sequencing. The relation between mutation status and cancer‐specific (CSS) and overall survival (OS) was analyzed using Kaplan–Meier and Cox regression analysis. BRAF V600E mutations were observed in 51% (n = 73) and KRAS mutations in 16% of cases (n = 23). Patients with double wild‐type cancers (dWT; i.e., BRAF and KRAS wild‐type) had a highly favourable survival with 5‐year CSS of 93% (95% CI 84–100%), while patients with cancers harbouring mutations in either BRAF or KRAS, had 5‐year CSS of 76% (95% CI 67–85%). In the subgroup of stage II patients with dWT cancers no cancer‐specific deaths were observed. On multivariate analysis, mutation in either BRAF or KRAS vs. dWT remained significantly prognostic. Mutations in BRAF as well as KRAS should be analyzed when considering these genes as prognostic markers in MSI colon cancers.

Comprehensive population-wide analysis of Lynch syndrome in Iceland reveals founder mutations in MSH6 and PMS2

Lynch syndrome, caused by germline mutations in the mismatch repair genes, is associated with increased cancer risk. Here using a large whole-genome sequencing data bank, cancer registry and colorectal tumour bank we determine the prevalence of Lynch syndrome, associated cancer risks and pathogenicity of several variants in the Icelandic population. We use colorectal cancer samples from 1,182 patients diagnosed between 2000–2009. One-hundred and thirty-two (11.2%) tumours are mismatch repair deficient per immunohistochemistry. Twenty-one (1.8%) have Lynch syndrome while 106 (9.0%) have somatic hypermethylation or mutations in the mismatch repair genes. The population prevalence of Lynch syndrome is 0.442%. We discover a translocation disrupting MLH1 and three mutations in MSH6 and PMS2 that increase endometrial, colorectal, brain and ovarian cancer risk. We find thirteen mismatch repair variants of uncertain significance that are not associated with cancer risk. We find that founder mutations in MSH6 and PMS2 prevail in Iceland unlike most other populations.

Immune checkpoint inhibition-related colitis: symptoms, endoscopic features, histology and response to management

Background Immune checkpoint inhibitors are successfully introduced as anticancer treatment. However, they may induce severe immune-related adverse events (irAEs). One of the most frequent irAEs is diarrhoea. The main objective of this study was to analyse symptoms (ie, grade of diarrhoea), endoscopic and histological features and response to management in immune checkpoint inhibition-related colitis (IRC). Patients and methods We retrospectively analysed patients who developed diarrhoea on checkpoint inhibition and therefore underwent an endoscopy and/or were treated with corticosteroids. Patients were treated between August 2010 and March 2016 for metastatic melanoma or non-small cell lung cancer. Severity of IRC was scored using the endoscopic Mayo score and the van der Heide score. Results Out of a cohort of 781 patients, 92 patients were identified who developed diarrhoea and therefore underwent an endoscopy and/or were treated with corticosteroids. Patients were treated with monotherapy anticytotoxic T-lymphocyte antigen-4, antiprogrammed death receptor-1 or a combination of both. All patients had symptoms of diarrhoea (grade 1: 16%; grade 2: 39% and grade 3: 44%). A complete colonoscopy was performed in 62 (67%) patients, of whom 42 (68%) had a pancolitis (≥3 affected segments). Ulcers were seen in 32% of endoscopies. There was no significant correlation between the grade of diarrhoea at presentation and endoscopic severity scores, the presence of ulcers or histological features. In 54 episodes of diarrhoea (56%), patients received one or more cycles infliximab for steroid-refractory colitis. Patients with higher endoscopic severity scores, ulcers and/or a pancolitis needed infliximab more often. Conclusions The correlation between grade of diarrhoea and endoscopic or histological features for severity of colitis is poor. Patients with higher endoscopic severity scores, ulcers or a pancolitis needed the addition of infliximab more often. Therefore, endoscopy may have value in the evaluation of the severity of IRC and may help in decision making for optimal management.

Fatal Hemothorax Caused by Pseudomesotheliomatous Carcinoma of the Lung

We present a case of a poorly differentiated pseudomesotheliomatous carcinoma originating in the lung, which was manifested with the distinctly rare complication of massive true hemothorax and persistent blood loss that proved rapidly fatal in spite of surgery. Pseudomesotheliomatous carcinoma of the lung and neoplasia-associated hemothorax are reviewed and discussed.

Diffuse reflectance spectroscopy as a tool for real-time tissue assessment during colorectal cancer surgery

Abstract. Colorectal surgery is the standard treatment for patients with colorectal cancer. To overcome two of the main challenges, the circumferential resection margin and postoperative complications, real-time tissue assessment could be of great benefit during surgery. In this ex vivo study, diffuse reflectance spectroscopy (DRS) was used to differentiate tumor tissue from healthy surrounding tissues in patients with colorectal neoplasia. DRS spectra were obtained from tumor tissue, healthy colon, or rectal wall and fat tissue, for every patient. Data were randomly divided into training (80%) and test (20%) sets. After spectral band selection, the spectra were classified using a quadratic classifier and a linear support vector machine. Of the 38 included patients, 36 had colorectal cancer and 2 had an adenoma. When the classifiers were applied to the test set, colorectal cancer could be discriminated from healthy tissue with an overall accuracy of 0.95 (±0.03). This study demonstrates the possibility to separate colorectal cancer from healthy surrounding tissue by applying DRS. High classification accuracies were obtained both in homogeneous and inhomogeneous tissues. This is a fundamental step toward the development of a tool for real-time in vivo tissue assessment during colorectal surgery.

Outcomes of screening gastroscopy in first-degree relatives of patients fulfilling hereditary diffuse gastric cancer criteria

BACKGROUND AND AIMS The aim of this study was to determine the yield of endoscopic screening in first-degree relatives (FDRs) of CDH1-negative hereditary diffuse-type gastric cancer (HDGC) patients. METHODS In this retrospective observational cohort study, in 2 expert centers in the Netherlands data were collected on FDRs from families fulfilling the international HDGC criteria that underwent endoscopic screening. Extensive inspection of the stomach was performed by gastroscopy, taking random and/or targeted stomach biopsy specimens to identify diffuse-type gastric cancer. RESULTS Between 2004 and 2016, 90 persons (40% men; mean age, 48 years) from 40 families were offered endoscopic screening. The mean number of endoscopies per person was 3. The mean follow-up time was 46 months and mean endoscopic interval 20 months. Signet ring cell carcinoma foci restricted to the mucosa (pT1a) were identified in 4 persons (4%) from 1 family, which afterward was diagnosed with a germline CTNNA1 mutation. Advanced poorly cohesive gastric carcinoma was diagnosed in 1 person from another family. Intestinal metaplasia was diagnosed in 38 persons (42%) and low-grade dysplasia in 4 persons (4%). Additionally, in 40 persons (44%) scar tissue was observed in the gastric mucosa, which can hinder the endoscopic detection of small white lesions typical for HDGC. CONCLUSIONS Endoscopic screening in HDGC families without a pathogenic CDH1 mutation may be reasonable, as we detected signet ring cell carcinomas in 6% of persons screened. However, the criteria and frequency of screening may have to be reconsidered.

Outcomes after prophylactic gastrectomy for hereditary diffuse gastric cancer

Patients with hereditary diffuse gastric cancer and a CDH1 mutation have a 60–80 per cent lifetime risk of developing diffuse gastric cancer. Total prophylactic gastrectomy eliminates this risk, but is associated with considerable morbidity. The effectiveness (removal of all gastric mucosa) and outcomes of this procedure were evaluated retrospectively.

Histopathological and molecular classification of colorectal cancer and corresponding peritoneal metastases

Patients with colorectal peritoneal carcinomatosis have a very poor prognosis. The recently developed consensus molecular subtype (CMS) classification of primary colorectal cancer categorizes tumours into four robust subtypes, which could guide subtype‐targeted therapy. CMS4, also known as the mesenchymal subtype, has the greatest propensity to form distant metastases. CMS4 status and histopathological features of colorectal peritoneal carcinomatosis were investigated in this study.