Surveillance for cancer and dysplasia in inflammatory bowel disease

Combined endocytoscopy with pit pattern diagnosis in ulcerative colitis-associated neoplasia: Pilot study

OBJECTIVES

Ulcerative colitis-associated neoplasias (UCAN) are often flat with an indistinct boundary from surrounding tissues, which makes differentiating UCAN from non-neoplasias difficult. Pit pattern (PIT) has been reported as one of the most effective indicators to identify UCAN. However, regenerated mucosa is also often diagnosed as a neoplastic PIT. Endocytoscopy (EC) allows visualization of cell nuclei. The aim of this retrospective study was to demonstrate the diagnostic ability of combined EC irregularly-formed nuclei with PIT (EC-IN-PIT) diagnosis to identify UCAN.

METHODS

This study involved patients with ulcerative colitis whose lesions were observed by EC. Each lesion was diagnosed by two independent expert endoscopists, using two types of diagnostic strategies: PIT alone and EC-IN-PIT. We evaluated and compared the diagnostic abilities of PIT alone and EC-IN-PIT. We also examined the difference in the diagnostic abilities of an EC-IN-PIT diagnosis according to endoscopic inflammation severity.

RESULTS

We analyzed 103 lesions from 62 patients; 23 lesions were UCAN and 80 were non-neoplastic. EC-IN-PIT diagnosis had a significantly higher specificity and accuracy compared with PIT alone: 84% versus 58% (P < 0.001), and 88% versus 67% (P < 0.01), respectively. The specificity and accuracy were significantly higher for Mayo endoscopic score (MES) 0-1 than MES 2-3: 93% versus 68% (P < 0.001) and 95% versus 74% (P < 0.001), respectively.

CONCLUSIONS

Our novel EC-IN-PIT strategy had a better diagnostic ability than PIT alone to predict UCAN from suspected and initially detected lesions using conventional colonoscopy. UMIN clinical trial (UMIN000040698).

Solute carrier family 12 member 2 as a proteomic and histological biomarker of dysplasia and neoplasia in ulcerative colitis

BACKGROUND AND AIMS

Ulcerative colitis (UC) patients have a greater risk of developing colorectal cancer through inflammation-dysplasia-carcinoma sequence of transformation. The histopathological diagnosis of dysplasia is therefore of critical clinical relevance, but dysplasia may be difficult to distinguish from inflammatory changes.

METHODS

A proteomic pilot study on 5 UC colorectal dysplastic patients highlighted proteins differentially distributed between paired dysplastic, inflammatory and normal tissues. The best candidate marker was selected and immunohistochemistry confirmation was performed on AOM/DSS mouse model lesions, 37 UC dysplasia, 14 UC cancers, 23 longstanding UC, 35 sporadic conventional adenomas, 57 sporadic serrated lesions and 82 sporadic colorectal cancers.

RESULTS

Differential proteomics found 11 proteins significantly more abundant in dysplasia compared to inflammation, including Solute carrier family 12 member 2 (SLC12A2) which was confidently identified with 8 specific peptides and was below the limit of quantitation in both inflammatory and normal colon. SLC12A2 immunohistochemical analysis confirmed the discrimination of preneoplastic and neoplastic lesions from inflammatory lesions in mice, UC and in sporadic contexts. A specific SLC12A2 staining pattern termed "loss of gradient" reached 89% sensitivity, 95% specificity and 92% accuracy for UC-dysplasia diagnosis together with an inter-observer agreement of 95.24% (multirater κfree of 0.90; IC95%: 0.78 - 1.00). Such discrimination could not be obtained by Ki67 staining. This specific pattern was also associated with sporadic colorectal adenomas and cancers.

CONCLUSIONS

We found a specific SLC12A2 immunohistochemical staining pattern in precancerous and cancerous colonic UC-lesions which could be helpful for diagnosing dysplasia and cancer in UC and non-UC patients.

Histopathological diagnosis of ulcerative colitis-associated neoplasia

In patients with ulcerative colitis, tumor development occurs with an increase in the duration of the disease. Such lesions, known as ulcerative colitis-associated neoplasia (UCAN), histologically show a broad variety of findings such as low-grade dysplasia, high-grade dysplasia, and invasive carcinoma. For pathologists, however, the histopathological diagnosis of UCAN is occasionally difficult. Problems in pathological diagnosis can be summarized into the following three categories: (i) difficulty in discriminating UCAN from non-neoplastic inflammatory change; (ii) difficulty in discriminating UCAN from sporadic epithelial neoplasm; and (iii) difficulty in histological grading of UCAN. For most lesions, pathologists can make conclusive histological diagnoses without any problems. However, pathologists occasionally face diagnostic difficulties, especially in cases of lesions with borderline or indefinite histology and, therefore, at least two experienced gastrointestinal pathologists are needed to confirm the diagnosis. Hence, a confirmation is usually preferable for the estimation of tumor depth and lymphovascular invasion in digestive tract cancers as well as in UCAN. Immunohistochemistry for p53 and Ki-67 (MIB-1) is occasionally useful as an ancillary tool. Since UCAN has distinct characteristics compared to sporadic epithelial neoplasia, its treatment strategy should be carefully discussed by a multidisciplinary team, especially for cases of lesions with indefinite histology. At present, although surgical intervention such as total colectomy is the most promising procedure for UCAN, recent advances in endoscopic diagnosis and therapy are expected to improve future treatment strategy.

The role of endoscopy in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of chronic immune-mediated disorders of the gastrointestinal tract. It is often the result of the interaction of genetic and environmental factors. The role of endoscopy in disease surveillance is unprecedented. However, there is considerable debate in therapeutic goals in IBD patients, ranging from the resolution of clinical symptoms to mucosal healing. Furthermore, deep remission has recently been advocated for altering disease course in these patients. Additionally, neoplasia continues to be a significant cause of morbidity and mortality in IBD patients. This review discussed the role of several endoscopic techniques in assessing mucosal healing and neoplasia with emphasis on novel non-invasive endoscopic techniques.

Use of surveillance colonoscopy in medicare patients with inflammatory bowel disease prior to colorectal cancer diagnosis

BACKGROUND

Patients with longstanding inflammatory bowel disease (IBD) involving large intestine proximal to rectum are considered to be at increased risk for colorectal cancer (CRC). One prior study showed low utilization of surveillance colonoscopy in patients with ≥ 8 years of ulcerative colitis (UC) in the USA.

AIMS

To study use of surveillance colonoscopy among Medicare beneficiaries with IBD in the 2-year period prior to CRC diagnosis.

DATA AND METHODS

Our study sample included Medicare beneficiaries in the SEER-Medicare-linked database who were diagnosed with CRC during 2001-2005 and had ≥ 3 physician visits with ICD-9 diagnosis code for IBD prior to CRC diagnosis. Medicare beneficiaries aged >85 years without Part B coverage or enrolled in HMOs were excluded. Colonoscopy performed within 6-30 months prior to CRC diagnosis was defined as surveillance colonoscopy. The χ² test and multivariate logistic regression were used in statistical analysis.

RESULTS

Of 241 Medicare beneficiaries with IBD and diagnosed with CRC, 92 (38%) patients underwent ≥ 1 surveillance colonoscopy in the 2 years prior to cancer diagnosis. The use of surveillance colonoscopy was similar between Crohn's disease (28/86, 33%) and UC (64/155, 41%). In multivariate logistic regression, older age (odds ratio (OR) 0.97, 95% confidence interval (CI) 0.94-0.99) was negative associated with surveillance colonoscopy use and personal history of colon polyp (OR 2.73, 95% CI 1.09-6.87) was positively associated with surveillance colonoscopy use.

CONCLUSIONS

Use of surveillance colonoscopy was low among Medicare beneficiaries with IBD in the 2 years prior to CRC diagnosis.

Advanced endoscopic imaging for surveillance for dysplasia and colorectal cancer in inflammatory bowel disease: could the pathologist be further helped?

Patients with inflammatory bowel disease (IBD) have an increased risk of developing intestinal cancer. The magnitude of that increased risk as well as how best to mitigate it remain a topic of ongoing investigation in the field. It is important to quantify the risk of colorectal cancer in association with IBD. The reported risk varies widely between studies. This is partly due to the different methodologies used in the studies. Because of the limitations of surveillance strategies based on the detection of dysplasia, advanced endoscopic imaging and techniques involving the detection of alterations in mucosal antigens and genetic abnormalities are being investigated. Development of new biomarkers, predicting future occurrence of colonic neoplasia may lead to more biomarker-based surveillance. There are promising results that may lead to more efficient surveillance in IBD patients and more general acceptance of its use. A multidisciplinary approach, involving in particular endoscopists and pathologists, together with a centralized patient management, could help to optimize treatments and follow-up measures, both of which could help to reduce the IBD-associated cancer risk.

Rate of early/missed colorectal cancers after colonoscopy in older patients with or without inflammatory bowel disease in the United States

OBJECTIVES

Patients with inflammatory bowel disease (IBD) have an increased risk for colorectal cancer (CRC). Previous studies on early/missed CRCs after colonoscopy excluded IBD patients. The aim of this study was to compare the rate of early/missed CRCs after colonoscopy among IBD and non-IBD patients, and identify factors associated with early/missed CRCs.

METHODS

All patients in the Surveillance, Epidemiology and End-Results Medicare-linked database who were 67 years or older at colonoscopy during 1998-2005 and those who were subsequently diagnosed with CRC within 36 months were identified. CRCs diagnosed within 6 months of colonoscopy were categorized as detected CRCs; CRCs diagnosed 6-36 months after colonoscopy were categorized as early/missed CRCs. The rate of early/missed CRCs was calculated as number of early/missed CRCs divided by number of detected and early/missed CRCs. The χ(2) test and multivariate logistic regression were used in statistical analysis.

RESULTS

Of 55,008 CRC patients (304 Crohn's disease; 544 ulcerative colitis (UC)), the rate of early/missed CRCs was 5.8% for non-IBD patients, 15.1% for Crohn's, and 15.8% for UC (P<0.001). Compared with older non-IBD patients, early/missed CRCs among older IBD patients were less likely right-sided (both P<0.05). In multivariate logistic regression, the risk of early/missed CRCs was three times as high for IBD patients (Crohn's odds ratio (OR), 3.07; 95% confidence interval (CI) 2.23-4.21; UC OR, 3.05; 95% CI, 2.44-3.81). Sensitivity analyses confirmed the robustness of this finding.

CONCLUSIONS

Older IBD patients had a higher rate of early/missed CRCs after colonoscopy. Our finding supports intensive surveillance colonoscopy for older IBD patients as recommended by guidelines.

Dysplasia in inflammatory bowel diseases

In both Crohn's disease and ulcerative colitis, the secondary prevention of colorectal cancer basically relies on the histological detection of dysplasia. In inflammatory bowel diseases, dysplasia identifies the subgroup of patients eligible for stricter surveillance (or prophylactic colectomy). In clinical practice, a number of issues may influence the benefits of clinico-pathological surveillance for inflammatory bowel disease patients with dysplasia, including: sampling errors, inconsistent biopsy assessments, patients' compliance with follow-up requirements, and how heath care is organized. Even in such a multifaceted context, it has been demonstrated that dysplasia surveillance is effective in reducing colorectal cancer-related mortality and morbidity. This paper focuses on current issues concerning the histological assessment of inflammatory bowel disease-associated dysplastic lesions.

Th17 cell accumulation is decreased during chronic experimental colitis by (n-3) PUFA in Fat-1 mice

During colon inflammation, Th17 cells and immunosuppressive regulatory T cells (Treg) are thought to play promotive and preventative roles, respectively. Dietary (n-3) PUFA favorably modulate intestinal inflammation in part by downregulating T-cell activation and functionality. We used the Fat-1 mouse, a genetic model that synthesizes long-chain (n-3) PUFA de novo, to test the hypothesis that (n-3) PUFA protect against colonic inflammation by modulating the polarization of Treg and Th17 cells during colitis. Male and female wild-type (WT) and Fat-1 mice were administered dextran sodium sulfate (DSS) in the drinking water (2.5%) to induce acute (5 d DSS) or chronic (3 cycles DSS) colitis and the percentage of Treg and Th17 cells residing locally [colonic lamina propria (cLP)] and systemically (spleen) was determined by flow cytometry. The percentage of Treg in either tissue site was unaffected by genotype (P > 0.05); however, during chronic colitis, the percentage of Th17 cells residing in both the spleen and cLP was lower in Fat-1 mice compared to WT mice (P < 0.05). Colonic mucosal mRNA expression of critical Th17 cell cytokines and chemokine receptors (IL-17F, IL-21, and CCR6) were lower, whereas expression of the Th17 cell suppressive cytokine, IL-27, was greater in Fat-1 mice compared to WT mice during chronic colitis (P < 0.05). Moreover, colon histological scores were improved in Fat-1 mice (P < 0.05). Collectively, these results demonstrate for the first time, to our knowledge, that (n-3) PUFA can modulate the colonic mucosal microenvironment to suppress Th17 cell accumulation and inflammatory damage following the induction of chronic colitis.

Immunomodulatory action of dietary fish oil and targeted deletion of intestinal epithelial cell PPARδ in inflammation-induced colon carcinogenesis

The ligand-activated transcription factor peroxisome proliferator-activated receptor (PPAR)-δ is highly expressed in colonic epithelial cells; however, the role of PPARδ ligands, such as fatty acids, in mucosal inflammation and malignant transformation has not been clarified. Recent evidence suggests that the anti-inflammatory/chemoprotective properties of fish oil (FO)-derived n-3 polyunsaturated fatty acids (PUFAs) may be partly mediated by PPARδ. Therefore, we assessed the role of PPARδ in modulating the effects of dietary n-3 PUFAs by targeted deletion of intestinal epithelial cell PPARδ (PPARδ(ΔIEpC)). Subsequently, we documented changes in colon tumorigenesis and the inflammatory microenvironment, i.e., local [mesenteric lymph node (MLN)] and systemic (spleen) T cell activation. Animals were fed chemopromotive [corn oil (CO)] or chemoprotective (FO) diets during the induction of chronic inflammation/carcinogenesis. Tumor incidence was similar in control and PPARδ(ΔIEpC) mice. FO reduced mucosal injury, tumor incidence, colonic STAT3 activation, and inflammatory cytokine gene expression, independent of PPARδ genotype. CD8(+) T cell recruitment into MLNs was suppressed in PPARδ(ΔIEpC) mice. Similarly, FO reduced CD8(+) T cell numbers in the MLN. Dietary FO independently modulated MLN CD4(+) T cell activation status by decreasing CD44 expression. CD11a expression by MLN CD4(+) T cells was downregulated in PPARδ(ΔIEpC) mice. Lastly, splenic CD62L expression was downregulated in PPARδ(ΔIEpC) CD4(+) and CD8(+) T cells. These data demonstrate that expression of intestinal epithelial cell PPARδ does not influence azoxymethane/dextran sodium sulfate-induced colon tumor incidence. Moreover, we provide new evidence that dietary n-3 PUFAs attenuate intestinal inflammation in an intestinal epithelial cell PPARδ-independent manner.

Cancer surveillance strategies in ulcerative colitis: the need for modernization

The risk of colorectal cancer is increased in patients with long-standing ulcerative colitis. Traditional surveillance has centered around regular standard white-light colonoscopy, with multiple biopsies aimed at detecting dysplasia or the identification of early cancer. This has resulted in only a modest reduction in cancer incidence and mortality. A better understanding of disease risk factors may allow endoscopic resources to be more focused on patients at higher risk. In addition, advanced endoscopic techniques have the potential to improve dysplasia detection, minimize the need for routine biopsies, and allow for the removal of dysplastic lesions, avoiding the need for surgery. Techniques such as magnification colonoscopy, chromoendoscopy, narrow band imaging, autofluorescence, and confocal endomicroscopy may all have a role to play in improving the benefits of endoscopic surveillance. Revised endoscopic surveillance strategies are proposed, incorporating aspects of risk stratification, a well-established practice in noncolitis-related colorectal cancer screening, and some of these new technologies.

Dietary fish oil and curcumin combine to modulate colonic cytokinetics and gene expression in dextran sodium sulphate-treated mice

Both fish oil (FO) and curcumin have potential as anti-tumour and anti-inflammatory agents. To further explore their combined effects on dextran sodium sulphate (DSS)-induced colitis, C57BL/6 mice were randomised to four diets (2 × 2 design) differing in fatty acid content with or without curcumin supplementation (FO, FO+2 % curcumin, maize oil (control, MO) or MO+2 % curcumin). Mice were exposed to one or two cycles of DSS in the drinking-water to induce either acute or chronic intestinal inflammation, respectively. FO-fed mice exposed to the single-cycle DSS treatment exhibited the highest mortality (40 %, seventeen of forty-three) compared with MO with the lowest mortality (3 %, one of twenty-nine) (P = 0·0008). Addition of curcumin to MO increased (P = 0·003) mortality to 37 % compared with the control. Consistent with animal survival data, following the one- or two-cycle DSS treatment, both dietary FO and curcumin promoted mucosal injury/ulceration compared with MO. In contrast, compared with other diets, combined FO and curcumin feeding enhanced the resolution of chronic inflammation and suppressed (P < 0·05) a key inflammatory mediator, NF-κB, in the colon mucosa. Mucosal microarray analysis revealed that dietary FO, curcumin and FO plus curcumin combination differentially modulated the expression of genes induced by DSS treatment. These results suggest that dietary lipids and curcumin interact to regulate mucosal homeostasis and the resolution of chronic inflammation in the colon.

Gastrointestinal cancer: current screening strategies

The prevention and chemoprevention of cancer is based on identifying a pre-neoplastic lesion and altering the outcome by early intervention. Many of the gastrointestinal epithelial cancers are related to chronic inflammatory conditions for many years prior to cancer development. It is clear that treatment of the inflammatory condition can prevent and indeed reverse changes that predispose to cancer. This is most notable for helicobacter pylori infection of the stomach. Screening for Barrett's oesophagus and other conditions are more controversial and the results of large scale clinical trials are awaited. Nevertheless preventive strategies are highly attract health care interventions and are being actively considered.

Prevalence of colorectal cancer surveillance for ulcerative colitis in an integrated health care delivery system

BACKGROUND & AIMS

The absence of grade A supporting evidence for surveillance colonoscopy in patients with ulcerative colitis (UC) has led to controversy regarding its benefit, yet it is routinely recommended in practice guidelines. Limited data are available on rates of colonoscopy surveillance and factors associated with surveillance.

METHODS

A retrospective study of UC patients receiving care between 2006 and 2007 with ≥ 8 years history of UC was conducted. Primary outcome was the proportion of patients who underwent surveillance during this 2-year study period. Sociodemographic and disease factors were identified a priori from variables recorded electronically in the medical record; multivariable associations with surveillance were estimated using logistic regression.

RESULTS

Of 771 patients with ≥ 8 years history of UC, 24.6% of patients underwent at least 1 surveillance colonoscopy within the 2-year study period, with a maximum of 38.5% observed among patients with primary sclerosing cholangitis. In a multivariable analysis, gender, age, race, and education were not associated with surveillance. Factors associated with increasing surveillance included lack of significant comorbidity (Charlson-Deyo index 0 vs 1+: odds ratio [OR], 1.7; 95% confidence interval: 1.1-2.5), > 3 inflammatory bowel disease-related outpatient visits (OR, 2.0; 95% CI: 1.4-3.0), and use of mesalamine (OR, 2.8; 95% CI: 1.7-4.4).

CONCLUSIONS

Utilization of surveillance colonoscopy in a 2-year period was low, even among high-risk patients. Although specific factors recorded in computerized data were identified to be associated with surveillance, a greater understanding of how patients and physicians decide on surveillance is needed.

Crohn's disease clinical issues and treatment: what the radiologist needs to know and what the gastroenterologist wants to know

Crohn's disease is an idiopathic chronic intestinal illness that requires specialized medical care for prompt disease diagnosis and appropriate management. Clinicians must accurately interpret and integrate findings from multitude of sources in order to achieve diagnostic certainty. Ileocolonoscopy remains the most relied modality, allowing for a direct mucosal visualization and biopsies for histologic assessments. Serologic markers currently serve an adjunctive role, often utilized in attempts to further subtype patients with indeterminate colitis. Radiologic imaging, such as computed tomography enterography can evaluate the far reaches of the small intestine, while also providing information about penetrating complications and extraintestinal disease manifestations. Treatment options and strategies continue to evolve with new biologic agents and ongoing testing of aggressive "top-down" approaches. In addition, identification of increased colorectal cancer risks in individuals with Crohn's colitis has led to formal surveillance guidelines. The clinical diagnosis and management of Crohn's disease continues to be an area of rapid change and exciting developments.

Positron emission tomography (PET) used to image subclinical inflammation associated with ulcerative colitis (UC) in remission

BACKGROUND

Positron emission tomography (PET) using 18-fluorodeoxyglucose (18-FDG) is a noninvasive, functional imaging modality most often used to assess cancer. The aim of this study was to perform PET/computed tomography (CT) on patients with quiescent ulcerative colitis (UC) to understand the limits of this technology for assessing inflammatory activity.

METHODS

We identified patients diagnosed with UC in a strictly defined remission state. PET/CT was performed in standard fashion, using approximately 10 mCi of 18-FDG with a 60-minute uptake delay. Uptake in each of 4 colonic segments (recto-sigmoid [r-s], descending, transverse, and ascending), and distal small bowel were scored on a 3-point scale (0 = no uptake or uptake <or=liver; 1 = uptake somewhat >liver; 2 = uptake much greater than liver).

RESULTS

Ten patients participated in this study, 6 male. Eight had pancolitis, 1 had extensive colitis, and 1 had procto-sigmoiditis, with a median disease duration was 32 years. A PET scan was performed mean 37 days after endoscopy. Six patients had no increased 18-FDG uptake, 3 had increased uptake in the r-s region, 1 patient with r-s uptake also had ascending colon uptake, and 1 had ileal uptake with no colonic signal.

CONCLUSIONS

In this study, PET demonstrated inflammatory activity in the colon despite negative endoscopic, histologic, and symptom assessment. This has important implications in the understanding of UC disease quiescence. Further exploration of this highly sensitive modality should be performed.

An updated approach to dysplasia in IBD

INTRODUCTION

Long-standing inflammation of the colorectum in ulcerative colitis (UC) and Crohn's disease (CD) has been associated with an increased risk of subsequent dysplasia and colorectal cancer. Historically, it was described that the neoplastic transformation in these inflammatory bowel diseases (IBDs) occurred via a different biologic pathway and not by the non-IBD polyp-cancer pathway and predictable lag time of progression. Therefore, prevention strategies have focused on the detection of dysplasia in flat mucosa, and existing guidelines have recommended performance of interval surveillance colonoscopies with random biopsies to identify such lesions with proctocolectomy when they are confirmed.

DISCUSSION

The use of a new technology higher-resolution colonoscopies has led to the appreciation more recently that dysplasia in IBD may be visible with standard optical colonoscopy and can be identified in an even more sensitive manner using chromoendoscopy. Furthermore, emerging evidence favors the intuitive understanding that neoplastic transformation in IBD is linked to the degree of inflammation and that disease control may therefore modify this risk and its subsequent prevention approaches.

CONCLUSION

Future IBD cancer prevention strategies and timing of surgery in at-risk patients will require a better understanding of this evolving field.

Chemoprevention of colorectal cancer: feasibility in everyday practice?

Chemoprevention means the use of agents to prevent, delay, or reverse carcinogenesis. This review was designed to critically discuss the most promising agents in colorectal cancer (CRC) chemoprevention. Aspirin is the best studied chemopreventive agent for CRC. Optimal chemoprevention requires long-term use and high dose of aspirin that may increase the risk of gastrointestinal bleeding. Nonsteroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors may also be candidates for chemoprevention. The regular use of nonsteroidal anti-inflammatory drugs, however, causes adverse effects including gastrointestinal bleeding, and cyclooxygenase-2 inhibitors may increase the risk of cardiovascular events. In patients with ulcerative colitis 5-aminosalicylates reduce the risk of CRC and dysplasia. Ursodeoxycholic acid can reduce the risk of dysplasia or CRC in patients with primary sclerosing cholangitis and ulcerative colitis. Current data are insufficient to support the use of hormone replacement therapy to reduce the risk of CRC. Statins may have chemopreventive effects, but further investigation of their overall benefits in preventing CRC is warranted. Antioxidant supplements cannot prevent CRC. The usefulness of selenium, folate, calcium, and vitamin D awaits further evaluation. Chemoprevention cannot yet be accepted as standard medical practice. Use of chemopreventive agents cannot be a substitute for colorectal surveillance.

Use of a novel genetic mouse model to investigate the role of folate in colitis-associated colon cancer

Inflammatory bowel disease (IBD) patients are at high risk for developing folate deficiency and colon cancer. Since it is difficult to study the subtle global and gene-specific epigenetic mechanisms involved in folate-mediated tumor initiation and promotion, we have generated genetically modified mouse models by targeting the reduced folate carrier (RFC1) and folate-binding protein (Folbp1) genes. The transgenic mice were fed semi-purified diets for 8 weeks containing either normal (2 mg) or deficient (0.1 mg folate/kg diet) levels of folate. Compound heterozygous mice (Folbp1(+/-); RFC1(+/-)) fed an adequate folate diet exhibited a reduction in plasma folate concentrations compared to heterozygous (Folbp1(+/-)) and littermate wild-type mice (P<.05). In contrast, no differences were observed in colonic mucosa. Consumption of a low folate diet significantly reduced (three- to fourfold) plasma and tissue folate levels in all animal models, although plasma homocysteine levels were not altered. In order to elucidate the relationship between folate status and inflammation-associated colon cancer, animals were injected with azoxymethane followed by dextran sodium sulphate treatment in the drinking water. Mice were fed a normal folate diet and were terminated 5 weeks after carcinogen injection. The number of high multiplicity aberrant crypt foci per centimeter of colon was significantly elevated (P<.05) in compound Folbp1(+/-); RFC1(+/-) (3.5+/-0.4) mice as compared to Folbp1(+/-) (1.9+/-0.3) and wild-type control mice (1.1+/-0.1). These data demonstrate that the ablation of two receptor/carrier-mediated pathways for folate transport increases the risk for developing inflammation-associated colon cancer.

Epigenetic regulation of WNT signaling pathway genes in inflammatory bowel disease (IBD) associated neoplasia

INTRODUCTION

WNT signaling pathway dysregulation is an important event in the pathogenesis of colorectal cancer (CRC) with APC mutations seen in more than 80% of sporadic CRC. However, such mutations in the WNT signaling pathway genes are rare in inflammatory bowel disease (IBD) associated neoplasia (dysplasia and cancer). This study examined the role of epigenetic silencing of WNT signaling pathway genes in the pathogenesis of IBD-associated neoplasia.

METHODS

Paraffin-embedded tissue samples were obtained and methylation of ten WNT signaling pathway genes, including APC1A, APC2, SFRP1, SFRP2, SFRP4, SFRP5, DKK1, DKK3, WIF1 and LKB1, was analyzed. Methylation analysis was performed on 41 IBD samples, 27 normal colon samples (NCs), and 24 sporadic CRC samples.

RESULTS

Methylation of WNT signaling pathway genes is a frequent and early event in IBD and IBD-associated neoplasia. A progressive increase in the percentage of methylated genes in the WNT signaling pathway from NCs (4.2%) to IBD colitis (39.7%) to IBD-associated neoplasia (63.4%) was seen (NCs vs. IBD colitis, p < 0.01; IBD colitis vs. IBD-associated neoplasia, p = 0.01). In the univariate logistic regression model, methylation of APC2 (OR 4.7, 95% CI: 1.1-20.63, p = 0.04), SFRP1 (OR 5.1, 95% CI: 1.1-31.9, p = 0.04), and SFRP2 (OR 5.1, 95% CI: 1.1-32.3, p = 0.04) was associated with progression from IBD colitis to IBD-associated neoplasia, while APC1A methylation was borderline significant (OR 4.1, 95% CI: 0.95-17.5, p = 0.06). In the multivariate logistic regression model, methylation of APC1A and APC2 was more likely to be associated with IBD-associated neoplasia than IBD colitis. (OR APC1A: 6.4, 95% CI: 1.1-37.7 p = 0.04; OR APC2 9.1, 95% CI: 1.3-61.7, p = 0.02).

SUMMARY

Methylation of the WNT signaling genes is an early event seen in patients with IBD colitis and there is a progressive increase in methylation of the WNT signaling genes during development of IBD-associated neoplasia. Moreover, methylation of APC1A, APC2, SFRP1, and SFRP2 appears to mark progression from IBD colitis to IBD-associated neoplasia, and these genes may serve as biomarkers for IBD-associated neoplasia.

Reduced colitis-associated colon cancer in Fat-1 (n-3 fatty acid desaturase) transgenic mice

Bioactive food components containing n-3 polyunsaturated fatty acids (PUFA) modulate multiple determinants that link inflammation to cancer initiation and progression. Therefore, in this study, fat-1 transgenic mice, which convert endogenous n-6 PUFA to n-3 PUFA in multiple tissues, were injected with azoxymethane followed by three cycles of dextran sodium sulfate (DSS) to induce colitis-associated cancer. Fat-1 mice exhibited a reduced number of colonic adenocarcinomas per mouse (1.05 +/- 0.29 versus 2.12 +/- 0.51, P = 0.033), elevated apoptosis (P = 0.03), and a decrease in n-6 PUFA-derived eicosanoids, compared with wild-type (wt) mice. To determine whether the chemoprotective effects of n-3 PUFA could be attributed to its pleiotropic anti-inflammatory properties, colonic inflammation and injury scores were evaluated 5 days after DSS exposure followed by either a 3-day or 2-week recovery period. There was no effect of n-3 PUFA at 3 days. However, following a 2-week recovery period, colonic inflammation and ulceration scores returned to pretreatment levels compared with 3-day recovery only in fat-1 mice. For the purpose of examining the specific reactivity of lymphoid elements in the intestine, CD3(+) T cells, CD4(+) T helper cells, and macrophages from colonic lamina propria were quantified. Comparison of 3-day versus 2-week recovery time points revealed that fat-1 mice exhibited decreased (P < 0.05) CD3(+), CD4(+) T helper, and macrophage cell numbers per colon as compared with wt mice. These results suggest that the antitumorigenic effect of n-3 PUFA may be mediated, in part, via its anti-inflammatory properties.

Colorectal cancer and dysplasia in inflammatory bowel disease

Both ulcerative colitis and Crohn’s disease carry an increased risk of developing colorectal cancer. Established risk factors for cancer among patients with inflammatory bowel disease (IBD) include the younger age at diagnosis, greater extent and duration of disease, increased severity of inflammation, family history of colorectal cancer and coexisting primary sclerosing cholangitis. Recent evidence suggests that current medical therapies and surgical techniques for inflammatory bowel disease may be reducing the incidence of this complication. Nonetheless heightened vigilance and a careful, comprehensive approach to prevent or minimize the complications of invasive cancer are warranted in this unique cohort of patients. Current guidelines for the prevention and early detection of cancer in this high risk population are grounded in the concept of an inflammation-dysplasia-carcinoma sequence. A thorough understanding of the definition and natural history of dysplasia in IBD, as well as the challenges associated with detection and interpretation of dysplasia are fundamental to developing an effective strategy for surveillance and prevention, and understanding the limitations of the current approach to prevention. This article reviews the current consensus guidelines for screening and surveillance of cancer in IBD, as well as presenting the evidence and rationale for chemoprevention of cancer and a discussion of emerging technologies for the detection of dysplasia.

Phenotype classification in IBD: Is there an impact on therapy?

This review summarizes the current phenotypic classifications of inflammatory bowel disease (IBD) and outlines their implications for diagnosis, therapy, prognosis, clinical trial design, and genotype-phenotype correlations.

Abnormal expression of M1/MUC5AC mucin in distal colon of patients with diverticulitis, ulcerative colitis and cancer

The abnormal expression of gastric M1/MUC5AC mucin in precancerous lesions and colon cancer evidenced by immunohistochemistry led us to check for its presence in the mucus obtained directly from patients undergoing surgery for cancerous (adenocarcinoma) or inflammatory (diverticulitis or ulcerative colitis) diseases. In parallel, the authors quantified aberrant crypt foci (ACF) and their immunolabelling by M1/MUC5AC in mucosae of cancer and diverticulitis patients. Immuno-Radio-Metric Assay of M1/MUC5AC mucin developed by the authors was used to detect M1/MUC5AC mucin in the colonic mucus scraped from surgical specimens. M1/MUC5AC mucin was detected in the mucus of 51/69 (74%) patients with colon adenocarcinoma, versus 7/27 (26%) patients with diverticulitis (threshold: 30 units of M1 mucin per mg protein, area under ROC curve: 0.80). M1/MUC5AC was present in significantly (p < 0.001) larger amounts in the mucus of cancer versus diverticulitis patients. All (10/10) patients with ulcerative colitis tested showed levels above the threshold and their mucosae were strongly labelled with the anti-M1/MUC5AC antibody by immunohistochemistry. Patients with cancer exhibited 3 fold more ACF than those with diverticulitis, but no significant difference was observed in the mean size and M1/MUC5AC expression pattern of ACF between these two groups. The expression of M1/MUC5AC was in correlation with their size. In macroscopically normal mucosa, ACF were the most important source of M1/MUC5AC mucin. Testing of M1/MUC5AC can enhance the detection of precancerous lesions and colon cancer.

Diagnostics of inflammatory bowel disease

The diagnosis of inflammatory bowel disease (IBD) with its 2 main subforms, Crohn's disease and ulcerative colitis, is based on clinical, endoscopic, radiologic, and histologic criteria. This paradigm remains unchanged despite the advent of new molecular technologies for the examination of serum proteins and genetic sequences, respectively. The main innovations in diagnostic technologies include the development of more sophisticated endoscopic and noninvasive imaging techniques with the aim of improving the identification of complications, in particular malignant diseases associated with IBD. The future will see further progress in the identification of genetic susceptibility factors and of protein biomarkers and their use to describe the molecular epidemiology of IBD. It can be expected that future diagnostic algorithms will include molecular parameters to detect early disease or guide therapies by predicting the individual course of disease.

Endoscopy/surveillance in inflammatory bowel disease

Patients with chronic colitis from inflammatory bowel disease (IBD) have an increased risk of colorectal cancer (CRC). Previously, to ameliorate this, prophylactic total colectomy was offered to patients who had chronic ulcerative colitis (UC); however, research has identified less invasive management options through better understanding of the pathogenesis of cancer in chronic inflammation, a more uniform histologic diagnosis by pathologists, and proper surveillance colonoscopy techniques. This article reviews the pathogenesis of neoplasia in IBD, and then reviews the risk factors for CRC in IBD, surveillance guidelines and their limitations, surveillance techniques, ileal pouch dysplasia, and chemoprevention. Although data for CRC risk in Crohn's disease (CD) are not as extensive, it has been suggested that the risks are comparable to UC.

Carcinogenesis in inflammatory bowel disease

Patients with longstanding ulcerative colitis (UC) and Crohn's disease (CD) have an increased risk of colorectal cancer (CRC). CRC accounts for approximately 15% of all deaths in patients with inflammatory bowel disease (IBD). The molecular pathway leading to CRC in IBD appears to differ from the well-known adenoma-to-CRC sequence, given the fact that these cancers appear to arise from either flat dysplastic tissue or dysplasia-associated lesions or masses. The risk of CRC for patients with IBD increases by 0.5-1% yearly, 8-10 years after diagnosis. Patients with a young age at disease onset, more extensive colitis, greater inflammatory burden, concomitant primary sclerosing cholangitis, and a family history of CRC are at greatest risk. Most cancers arise in pancolitis and there is little or no increased risk associated with proctitis while left-sided colitis carries an intermediate cancer risk. The CRC risk in patients with colonic CD is similar to that of UC. Colonic dysplasia is a precursor to CRC in IBD. There is no clear evidence that surveillance colonoscopy prolongs survival in patients with extensive colitis. Newer endoscopic and molecular techniques are being assessed for their effectiveness in augmenting conventional surveillance.