PREF-NET: a patient preference and experience study of lanreotide autogel administered in the home versus hospital setting among patients with gastroenteropancreatic neuroendocrine tumours in the UK.

PURPOSE: PREF-NET reported patients' experience of Somatuline® (lanreotide) Autogel® (LAN) administration at home and in hospital among patients with gastroenteropancreatic neuroendocrine tumours (GEP-NETs). METHODS: PREF-NET was a multicentre, cross-sectional study of UK adults (aged ≥ 18 years) with GEP-NETs receiving a stable dose of LAN, which comprised of (1) a quantitative online survey, and (2) qualitative semi-structured interviews conducted with a subgroup of survey respondents. The primary objective was the description of overall patient preference for home versus hospital administration of LAN. Secondary objectives included describing patient-reported opinions on the experience and associated preference for each administration setting, and the impact on healthcare utilisation, societal cost, activities of daily living and health-related quality of life (HRQoL). RESULTS: In the primary analysis (80 patients; mean age 63.9 years), 98.7% (95% confidence interval [CI]: 96.1-100.0) of patients preferred to receive LAN at home, compared with 1.3% (95% CI: 0.0-3.9) who preferred the hospital setting. Among participants, over half (60.3%) received their injection from a non-healthcare professional. Most patients (79.5% [95% CI: 70.5-88.4]) reported a positive effect on HRQoL after the switch from hospital to home administration. Qualitative interviews (20 patients; mean age 63.6 years) highlighted that patients preferred home administration because it improved overall convenience; saved time and costs; made them feel more comfortable and relaxed, and less stressed; and increased confidence in their ability to self-manage their treatment. CONCLUSION: Almost all patients preferred to receive LAN treatment at home rather than in hospital with increased convenience and psychological benefits reported as key reasons for this preference.

Nfkb2 deficiency and its impact on plasma cells and immunoglobulin expression in murine small intestinal mucosa.

The alternative (noncanonical) nuclear factor-κB (NF-κB) signaling pathway predominantly regulates the function of the p52/RelB heterodimer. Germline Nfkb2 deficiency in mice leads to loss of p100/p52 protein and offers protection against a variety of gastrointestinal conditions, including azoxymethane/dextran sulfate sodium (DSS)-induced colitis-associated cancer and lipopolysaccharide (LPS)-induced small intestinal epithelial apoptosis. However, the common underlying protective mechanisms have not yet been fully elucidated. We applied high-throughput RNA-Seq and proteomic analyses to characterize the transcriptional and protein signatures of the small intestinal mucosa of naïve adult Nfkb2-/- mice. Those data were validated by immunohistochemistry and quantitative ELISA using both small intestinal tissue lysates and serum. We identified a B-lymphocyte defect as a major transcriptional signature in the small intestinal mucosa and immunoglobulin A as the most downregulated protein by proteomic analysis in Nfkb2-/- mice. Small intestinal immunoglobulins were dramatically dysregulated, with undetectable levels of immunoglobulin A and greatly increased amounts of immunoglobulin M being detected. The numbers of IgA-producing, cluster of differentiation (CD)138-positive plasma cells were also reduced in the lamina propria of the small intestinal villi of Nfkb2-/- mice. This phenotype was even more striking in the small intestinal mucosa of RelB-/- mice, although these mice were equally sensitive to LPS-induced intestinal apoptosis as their RelB+/+ wild-type counterparts. NF-κB2/p52 deficiency confers resistance to LPS-induced small intestinal apoptosis and also appears to regulate the plasma cell population and immunoglobulin levels within the gut.NEW & NOTEWORTHY Novel transcriptomic analysis of murine proximal intestinal mucosa revealed an unexpected B cell signature in Nfkb2-/- mice. In-depth analysis revealed a defect in the CD38+ B cell population and a gut-specific dysregulation of immunoglobulin levels.

New Developments in Gastric Neuroendocrine Neoplasms.

PURPOSE OF REVIEW: Gastric neuroendocrine neoplasms (g-NENs) are a rare type of stomach cancer. The three main subtypes have different pathogeneses, biological behaviours and clinical characteristics, so they require different management strategies. This article will provide an overview of g-NENs and highlight recent advances in the field. RECENT FINDINGS: Molecular profiling has revealed differences between indolent and aggressive g-NENs, as well as a new somatic mutation responsible for some familial type I g-NENs. Novel biomarkers have been developed which will hopefully improve diagnosis, treatment, risk stratification and follow-up. Patient treatment is also changing, as evidence supports the use of less aggressive options (e.g. endoscopic surveillance or resection) in some patients with more indolent tumours. g-NEN heterogeneity poses challenges in understanding and managing this rare disease. More basic science research is needed to investigate molecular pathogenesis, and future larger clinical studies will hopefully also further improve treatment and patient outcomes.

British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults.

Iron deficiency anaemia (IDA) is a major cause of morbidity and burden of disease worldwide. It can generally be diagnosed by blood testing and remedied by iron replacement therapy (IRT) using the oral or intravenous route. The many causes of iron deficiency include poor dietary intake and malabsorption of dietary iron, as well as a number of significant gastrointestinal (GI) pathologies. Because blood is iron-rich it can result from chronic blood loss, and this is a common mechanism underlying the development of IDA-for example, as a consequence of menstrual or GI blood loss.Approximately a third of men and postmenopausal women presenting with IDA have an underlying pathological abnormality, most commonly in the GI tract. Therefore optimal management of IDA requires IRT in combination with appropriate investigation to establish the underlying cause. Unexplained IDA in all at-risk individuals is an accepted indication for fast-track secondary care referral in the UK because GI malignancies can present in this way, often in the absence of specific symptoms. Bidirectional GI endoscopy is the standard diagnostic approach to examination of the upper and lower GI tract, though radiological scanning is an alternative in some situations for assessing the large bowel. In recurrent or refractory IDA, wireless capsule endoscopy plays an important role in assessment of the small bowel.IDA may present in primary care or across a range of specialties in secondary care, and because of this and the insidious nature of the condition it has not always been optimally managed despite the considerable burden of disease- with investigation sometimes being inappropriate, incorrectly timed or incomplete, and the role of IRT for symptom relief neglected. It is therefore important that contemporary guidelines for the management of IDA are available to all clinicians. This document is a revision of previous British Society of Gastroenterology guidelines, updated in the light of subsequent evidence and developments.

Carcinoid Heart Disease: Prognostic Value of 5-Hydroxyindoleacetic Acid Levels and Impact on Survival: A Systematic Literature Review.

BACKGROUND: Carcinoid heart disease (CHD) can develop in patients with carcinoid syndrome (CS), itself caused by overproduction of hormones and other products from some neuroendocrine tumours. The most common hormone is serotonin, detected as high 5-hydroxyindoleacetic acid (5-HIAA). This systematic literature review summarises current literature on the impact of CHD on survival, and the relationship between 5-HIAA levels and CHD development, progression, and mortality. METHODS: MEDLINE, Embase, Cochrane databases, and grey literature were searched using terms for CHD, 5-HIAA, disease progression, and mortality/survival. Eligible articles were non-interventional and included patients with CS and predefined CHD and 5-HIAA outcomes. RESULTS: Publications reporting on 31 studies were included. The number and disease states of patients varied between studies. Estimates of CHD prevalence and incidence among patients with a diagnosis/symptoms indicative of CS were 3-65% and 3-42%, respectively. Most studies evaluating survival found significantly higher mortality rates among patients with versus without CHD. Patients with CHD reportedly had higher 5-HIAA levels; median urinary levels in patients with versus without CHD were 266-1,381 versus 67.5-575 µmol/24 h. Higher 5-HIAA levels were also found to correlate with disease progression (median progression/worsening-associated levels: 791-2,247 µmol/24 h) and increased odds of death (7% with every 100 nmol/L increase). CONCLUSIONS: Despite the heterogeneity of studies, the data indicate that CHD reduces survival, and higher 5-HIAA levels are associated with CHD development, disease progression, and increased risk of mortality; 5-HIAA levels should be carefully managed in these patients.

A "Watch and Wait" Strategy Involving Regular Endoscopic Surveillance Is Safe for Many Patients with Small, Sporadic, Grade 1, Non-Ampullary, Non-Functioning Duodenal Neuroendocrine Tumours.

INTRODUCTION: Duodenal neuroendocrine tumours (d-NETs) are rare but are increasing in incidence. Current ENETS guidelines advocate resection of all localized d-NETs. However, "watch and wait" may be appropriate for some localized, small, grade 1, non-functioning, non-ampullary d-NETs. We evaluated whether patients with such d-NETs who chose "watch and wait" involving regular endoscopic surveillance had equivalent disease-related outcomes to patients undergoing endoscopic or surgical resection. METHODS: Retrospective review of patients with histologically confirmed d-NETs at Liverpool ENETS Centre of Excellence 2007-2020. RESULTS: Sixty-nine patients were diagnosed with d-NET of which 50 were sporadic, non-functioning, non-ampullary tumours. Patient treatment groups were similar in terms of age, gender, and tumour location and grade, but unsurprisingly, larger tumours (median diameter 17 mm [p < 0.0001]) were found in the surgically treated group. Five patients underwent surgical resection with no evidence of tumour recurrence or disease-related death. Twelve patients underwent endoscopic resection (ER), with 1 local recurrence detected during follow-up. Thirty patients (28 with d-NETs ≤10 mm) underwent "watch and wait" with resection only if tumours increased in size. The d-NETs in 28/30 patients remained stable or decreased in size over a median 27 months (IQR: 15-48, R: 3-98). In 7 patients, the d-NET was completely removed by avulsion during diagnostic biopsy and was not seen at subsequent endoscopies. Only 2 patients showed increased d-NET size during surveillance, of whom only one was fit for ER. No NET-related deaths were documented during follow-up. CONCLUSIONS: All of the localized, ≤10 mm, grade 1, non-functioning, non-ampullary d-NETs in this cohort behaved indolently with very low risks of progression and no tumour-related deaths. "Watch and wait," therefore, appears to be a safe alternative management strategy for selected d-NETs.

Potential role of fecal volatile organic compounds as biomarkers of chemically induced intestinal inflammation in mice.

Metabolomics studies have the potential to discover biomarkers. Fecal volatile organic compounds (VOCs) have been found to differ in patients with inflammatory bowel disease and irritable bowel syndrome. Murine models of colitis offer an alternative to human studies in which diet can be controlled. We aimed to investigate fecal VOCs from mice in which acute and chronic colitis was induced. Groups of adult C57BL/6 mice underwent treatment with oral dextran sulfate sodium to induce colitis. Control mice received no treatment or had acute osmotic diarrhea induced with magnesium sulfate. Colitis was assessed clinically and by histology. Samples of feces and/or colon contents were collected and volatile compounds determined by solid phase microextraction-GC-MS. Statistics were performed using metabolomics tools. Acute colitis was associated with an increase in aldehydes and chronic colitis with one specific ketone. Osmotic diarrhea was associated with a significant reduction in VOCs, especially alcohols. We provide evidence that the identification of disease-associated VOC concentration ranges, combined with specific marker compounds, would potentially increase the likelihood of finding an inflammatory bowel disease-specific fecal VOC marker profile.-Reade, S., Williams, J. M., Aggio, R., Duckworth, C. A., Mahalhal, A., Hough, R., Pritchard, D. M., Probert, C. S., Potential role of fecal volatile organic compounds as biomarkers of chemically induced intestinal inflammation in mice.

British Society of Gastroenterology guidelines on the diagnosis and management of patients at risk of gastric adenocarcinoma.

Gastric adenocarcinoma carries a poor prognosis, in part due to the late stage of diagnosis. Risk factors include Helicobacter pylori infection, family history of gastric cancer-in particular, hereditary diffuse gastric cancer and pernicious anaemia. The stages in the progression to cancer include chronic gastritis, gastric atrophy (GA), gastric intestinal metaplasia (GIM) and dysplasia. The key to early detection of cancer and improved survival is to non-invasively identify those at risk before endoscopy. However, although biomarkers may help in the detection of patients with chronic atrophic gastritis, there is insufficient evidence to support their use for population screening. High-quality endoscopy with full mucosal visualisation is an important part of improving early detection. Image-enhanced endoscopy combined with biopsy sampling for histopathology is the best approach to detect and accurately risk-stratify GA and GIM. Biopsies following the Sydney protocol from the antrum, incisura, lesser and greater curvature allow both diagnostic confirmation and risk stratification for progression to cancer. Ideally biopsies should be directed to areas of GA or GIM visualised by high-quality endoscopy. There is insufficient evidence to support screening in a low-risk population (undergoing routine diagnostic oesophagogastroduodenoscopy) such as the UK, but endoscopic surveillance every 3 years should be offered to patients with extensive GA or GIM. Endoscopic mucosal resection or endoscopic submucosal dissection of visible gastric dysplasia and early cancer has been shown to be efficacious with a high success rate and low rate of recurrence, providing that specific quality criteria are met.

Comparison of the human gastric microbiota in hypochlorhydric states arising as a result of Helicobacter pylori-induced atrophic gastritis, autoimmune atrophic gastritis and proton pump inhibitor use.

Several conditions associated with reduced gastric acid secretion confer an altered risk of developing a gastric malignancy. Helicobacter pylori-induced atrophic gastritis predisposes to gastric adenocarcinoma, autoimmune atrophic gastritis is a precursor of type I gastric neuroendocrine tumours, whereas proton pump inhibitor (PPI) use does not affect stomach cancer risk. We hypothesised that each of these conditions was associated with specific alterations in the gastric microbiota and that this influenced subsequent tumour risk. 95 patients (in groups representing normal stomach, PPI treated, H. pylori gastritis, H. pylori-induced atrophic gastritis and autoimmune atrophic gastritis) were selected from a cohort of 1400. RNA extracted from gastric corpus biopsies was analysed using 16S rRNA sequencing (MiSeq). Samples from normal stomachs and patients treated with PPIs demonstrated similarly high microbial diversity. Patients with autoimmune atrophic gastritis also exhibited relatively high microbial diversity, but with samples dominated by Streptococcus. H. pylori colonisation was associated with decreased microbial diversity and reduced complexity of co-occurrence networks. H. pylori-induced atrophic gastritis resulted in lower bacterial abundances and diversity, whereas autoimmune atrophic gastritis resulted in greater bacterial abundance and equally high diversity compared to normal stomachs. Pathway analysis suggested that glucose-6-phospahte1-dehydrogenase and D-lactate dehydrogenase were over represented in H. pylori-induced atrophic gastritis versus autoimmune atrophic gastritis, and that both these groups showed increases in fumarate reductase. Autoimmune and H. pylori-induced atrophic gastritis were associated with different gastric microbial profiles. PPI treated patients showed relatively few alterations in the gastric microbiota compared to healthy subjects.

68Gallium DOTANOC-PET Imaging in Lung Carcinoids: Impact on Patients' Management.

BACKGROUND: 68Gallium DOTA-PET imaging is preferable to standard somatostatin receptor scintigraphy where available; however, its role in the management of lung carcinoid tumours (LC) remains unclear. METHODS: All consecutive patients with histologically confirmed LC from two ENETS Centres of Excellence were identified retrospectively. The primary objective was to assess the impact of 68Ga-DOTANOC-PET on clinical management in patients with LC. RESULTS: Of 166 patients screened, 46 were eligible: 52% female, median age 57 years (range 21-86); type of LC: diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (4%), typical (44%), atypical (35%), not reported (17%); stage: localised (63%), locally advanced (13%), and metastatic (17%) (7% unknown). A total of 47 68Ga-DOTANOCs were performed with the following rationale: LC diagnosis confirmation (4; 9%), primary tumour identification (2; 4%), post-surgical assessment (19; 40%), staging (patients with known LC present at time of 68Ga-DOTANOC) (19; 40%), and consideration of peptide receptor radionuclide therapy (3; 7%). Twenty-seven (57%) scans showed evidence of non-physiological uptake: median maximum standardised uptake value 7.2 (range 1.42-53). 68Ga-DOTANOC provided additional information in 37% (95% CI 22-51) of patients and impacted on management in 26% (95% CI 12-41); 9 patients (21%) were identified to have occult sites of metastases. Out of the 19 patients with post-surgical 68Ga-DOTANOC, 3 (16%) were identified to have distant metastases. There were no differences in the rate of practice changing 68Ga-DOTANOC results by type of LC (p value 0.5). CONCLUSIONS: Our results support the role of 68Ga-DOTANOC for optimising the management of patients with LC, including post-surgical re-staging due to the potential for identifying occult metastases.

Application of a quantum cascade laser aperture scanning near-field optical microscope to the study of a cancer cell.

This work reports the first images obtained by combining an infrared aperture scanning near-field optical microscope (SNOM) with a quantum cascade laser (QCL). The future potential of this set-up is demonstrated by a preliminary study on an OE33 human oesophageal adenocarcinoma cell in which the cell is imaged at 1751 cm-1, 1651 cm-1, 1539 cm-1 and 1242 cm-1. In addition to the 1651 cm-1 image, three other images were acquired within the Amide I band (1689 cm-1, 1675 cm-1 and 1626 cm-1) chosen to correspond to secondary structures of proteins. The four images obtained within the Amide I band show distinct differences demonstrating the potential of this approach to reveal subtle changes in the chemical composition of a cell.

Quality standards in upper gastrointestinal endoscopy: a position statement of the British Society of Gastroenterology (BSG) and Association of Upper Gastrointestinal Surgeons of Great Britain and Ireland (AUGIS).

This document represents the first position statement produced by the British Society of Gastroenterology and Association of Upper Gastrointestinal Surgeons of Great Britain and Ireland, setting out the minimum expected standards in diagnostic upper gastrointestinal endoscopy. The need for this statement has arisen from the recognition that while technical competence can be rapidly acquired, in practice the performance of a high-quality examination is variable, with an unacceptably high rate of failure to diagnose cancer at endoscopy. The importance of detecting early neoplasia has taken on greater significance in this era of minimally invasive, organ-preserving endoscopic therapy. In this position statement we describe 38 recommendations to improve diagnostic endoscopy quality. Our goal is to emphasise practices that encourage mucosal inspection and lesion recognition, with the aim of optimising the early diagnosis of upper gastrointestinal disease and improving patient outcomes.

Exome sequencing identifies ATP4A gene as responsible of an atypical familial type I gastric neuroendocrine tumour.

Gastric neuroendocrine tumours (NETs) arise from enterochromaffin-like cells, which are located in oxyntic glands within the stomach. Type I tumours represent 70-80% of gastric NETs and are associated with hypergastrinaemia, chronic atrophic gastritis and achlorhydria. Gastrin is involved in the endocrine regulation of gastric acid production. Most type I gastric NETs are sporadic, have a good prognosis and their genetic basis are unknown. We performed an exome sequencing study in a family with consanguineous parents and 10 children, five of whom were affected by type I gastric NET. Atypical clinical traits included an earlier age of onset (around 30 years), aggressiveness (three had nodal infiltration requiring total gastrectomy and one an adenocarcinoma) and iron-deficiency rather than megaloblastic anaemia. We identified a homozygous missense mutation in the 14th exon of the ATP4A gene (c.2107C>T), which encodes the proton pump responsible for acid secretion by gastric parietal cells. The amino acid p.Arg703Cys is highly conserved across species and originates a change of one of the transmembrane domains that avoids the liberation of protons from cells to stomach. This is consistent with the achlorhydria that was observed in the affected individuals. No germline or somatic mutations in the ATP4A gene were found in sporadic gastric NET patients. Based on the results of this large family, it seems that this atypical form of gastric NET has an earlier age of onset, behaves more aggressively and has atypical clinical traits that differentiated from other studied cases.

Netazepide, a gastrin/cholecystokinin-2 receptor antagonist, can eradicate gastric neuroendocrine tumours in patients with autoimmune chronic atrophic gastritis.

AIMS: Netazepide, a gastrin/cholecystokinin 2 receptor antagonist, once daily for 12 weeks reduced the number of tumours and size of the largest one in 16 patients with autoimmune chronic atrophic gastritis (CAG), achlorhydria, hypergastrinaemia and multiple gastric neuroendocrine tumours (type 1 gastric NETs), and normalized circulating chromogranin A (CgA) produced by enterochromaffin-like cells, the source of the tumours. The aim was to assess whether longer-term netazepide treatment can eradicate type 1 gastric NETs. METHODS: After a mean 14 months off netazepide, 13 of the 16 patients took it for another 52 weeks. Assessments were: gastroscopy; gene-transcript expression in corpus biopsies using quantitative polymerase chain reaction; blood CgA and gastrin concentrations; and safety assessments. RESULTS: While off-treatment, the number of tumours, the size of the largest one, and CgA all increased again. Netazepide for 52 weeks: cleared all tumours in 5 patients; cleared all but one tumour in one patient; reduced the number of tumours and size of the largest one in the other patients; normalized CgA in all patients; and reduced mRNA abundances of CgA and histidine decarboxylase in biopsies. Gastrin did not increase further, confirming that the patients had achlorhydria. Netazepide was safe and well tolerated. CONCLUSIONS: A gastrin/cholecystokinin 2 receptor antagonist is a potential medical and targeted treatment for type 1 gastric NETs, and an alternative to regular gastroscopy or surgery. Treatment should be continuous because the tumours will regrow if it is stopped. Progress can be monitored by CgA in blood or biomarkers in mucosal biopsies.

PAK1 modulates a PPARγ/NF-κB cascade in intestinal inflammation.

P21-activated kinases (PAKs) are multifunctional effectors of Rho GTPases with both kinase and scaffolding activity. Here, we investigated the effects of inflammation on PAK1 signaling and its role in colitis-driven carcinogenesis. PAK1 and p-PAK1 (Thr423) were assessed by immunohistochemistry, immunofluorescence, and Western blot. C57BL6/J wildtype mice were treated with a single intraperitoneal TNFα injection. Small intestinal organoids from these mice and from PAK1-KO mice were cultured with TNFα. NF-κB and PPARγ were analyzed upon PAK1 overexpression and silencing for transcriptional/translational regulation. PAK1 expression and activation was increased on the luminal intestinal epithelial surface in inflammatory bowel disease and colitis-associated cancer. PAK1 was phosphorylated upon treatment with IFNγ, IL-1ß, and TNFα. In vivo, mice administered with TNFα showed increased p-PAK1 in intestinal villi, which was associated with nuclear p65 and NF-κB activation. p65 nuclear translocation downstream of TNFα was strongly inhibited in PAK1-KO small intestinal organoids. PAK1 overexpression induced a PAK1-p65 interaction as visualized by co-immunoprecipitation, nuclear translocation, and increased NF-κB transactivation, all of which were impeded by kinase-dead PAK1. Moreover, PAK1 overexpression downregulated PPARγ and mesalamine recovered PPARγ through PAK1 inhibition. On the other hand PAK1 silencing inhibited NF-κB, which was recovered using BADGE, a PPARγ antagonist. Altogether these data demonstrate that PAK1 overexpression and activation in inflammation and colitis-associated cancer promote NF-κB activity via suppression of PPARγ in intestinal epithelial cells.

Importance of the alternative NF-κB activation pathway in inflammation-associated gastrointestinal carcinogenesis.

Chronic inflammation is a common factor in the development of many gastrointestinal malignancies. Examples include inflammatory bowel disease predisposing to colorectal cancer, Barrett's esophagus as a precursor of esophageal adenocarcinoma, and Helicobacter pylori-induced gastric cancer. The classical activation pathway of NF-κB signaling has been identified as regulating several sporadic and inflammation-associated gastrointestinal tract malignancies. Emerging evidence suggests that the alternative NF-κB signaling pathway also exerts a distinct influence on these processes. This review brings together current knowledge of the role of the alternative NF-κB signaling pathway in the gastrointestinal tract, with a particular emphasis on inflammation-associated cancer development.

NF-κB1, NF-κB2 and c-Rel differentially regulate susceptibility to colitis-associated adenoma development in C57BL/6 mice.

NF-κB signalling is an important factor in the development of inflammation-associated cancers. Mouse models of Helicobacter-induced gastric cancer and colitis-associated colorectal cancer have demonstrated that classical NF-κB signalling is an important regulator of these processes. In the stomach, it has also been demonstrated that signalling involving specific NF-κB proteins, including NF-κB1/p50, NF-κB2/p52, and c-Rel, differentially regulate the development of gastric pre-neoplasia. To investigate the effect of NF-κB subunit loss on colitis-associated carcinogenesis, we administered azoxymethane followed by pulsed dextran sodium sulphate to C57BL/6, Nfkb1(-/-), Nfkb2(-/-), and c-Rel(-/-) mice. Animals lacking the c-Rel subunit were more susceptible to colitis-associated cancer than wild-type mice, developing 3.5 times more colonic polyps per animal than wild-type mice. Nfkb2(-/-) mice were resistant to colitis-associated cancer, developing fewer polyps per colon than wild-type mice (median 1 compared to 4). To investigate the mechanisms underlying these trends, azoxymethane and dextran sodium sulphate were administered separately to mice of each genotype. Nfkb2(-/-) mice developed fewer clinical signs of colitis and exhibited less severe colitis and an attenuated cytokine response compared with all other groups following DSS administration. Azoxymethane administration did not fully suppress colonic epithelial mitosis in c-Rel(-/-) mice and less colonic epithelial apoptosis was also observed in this genotype compared to wild-type counterparts. These observations demonstrate different functions of specific NF-κB subunits in this model of colitis-associated carcinogenesis. NF-κB2/p52 is necessary for the development of colitis, whilst c-Rel-mediated signalling regulates colonic epithelial cell turnover following DNA damage.