Intestinal cancer in patients with Crohn's disease: A systematic review and meta-analysis

Inflammation-Associated Carcinogenesis in Inflammatory Bowel Disease: Clinical Features and Molecular Mechanisms

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), is a chronic condition marked by persistent intestinal inflammation of unknown etiology. Disease onset involves genetic predisposition and environmental factors that disrupt the intestinal immune homeostasis. The intestinal microbiome and immune response play pivotal roles in disease progression. Advances in molecular therapies and early interventions have reduced surgery rates; however, colorectal cancer (CRC) remains a significant concern, driven by chronic inflammation. In UC, the risk of UC-associated neoplasia (UCAN) increases with disease duration, while CD patients face elevated risks of small intestine, anal fistula, and anal canal cancers. Endoscopic surveillance is advised for UCAN, but optimal screening intervals remain undefined, and no established guidelines exist for CD-associated cancers. UCAN morphology often complicates detection due to its flat, inflammation-blended appearance, which differs pathologically from sporadic CRC (sCRC). UCAN is frequently surrounded by dysplasia, with p53 mutations evident at the dysplasia stage. IBD-associated gastrointestinal cancers exemplify inflammation-driven carcinogenesis with distinct molecular mechanisms from the adenoma-carcinoma sequence. This review explores the epidemiology, risk factors, clinical and pathological features, current surveillance practices, and molecular pathways underlying inflammation-associated cancers in IBD.

Guidelines for endoscopic diagnosis and treatment of inflammatory bowel diseases

In recent years, we have seen a considerable increase in the number of patients with inflammatory bowel diseases of unknown etiology, including both Crohn's disease and ulcerative colitis. Inflammatory bowel diseases can cause intestinal lesions throughout the gastrointestinal tract, necessitating gastrointestinal endoscopy for examining all relevant aspects, especially lesion characteristics, for differential diagnosis and histological diagnosis, to select the appropriate treatment options, determine treatment effectiveness, etc. Specific guidelines are necessary to ensure that endoscopy can be performed in a safe and more tailored and efficient manner, especially since gastrointestinal endoscopy, including enteroscopy, is a common procedure worldwide, including in Japan. Within this context, the Japan Gastroenterological Endoscopy Society has formulated the "Guidelines for the Endoscopic Diagnosis and Treatment of Inflammatory Bowel Diseases" to provide detailed guidelines regarding esophagogastroduodenoscopy, enteroscopy, and colonoscopy procedures for definitive diagnosis, as well as determination of treatment effectiveness in clinical cases of inflammatory bowel diseases.

Surgery for Colorectal Cancer Associated with Crohn's Disease-Toward a Medical Treatment Strategy Based on the Differences Between Japan and Western Countries

With advances in the treatment of Crohn's disease (CD), the number of long-term cases is increasing, along with the incidence of CD-related cancers. Here, we discuss the clinical features, diagnosis, treatment, prognosis, and surveillance of CD-related cancers. There are regional differences in the common sites and histological types of CD-related cancers, with right-sided colon cancer accounting for 40% of cases in Europe and the US, and squamous cell carcinoma being common. In Japan, rectal and anal cancers account for 80% of cases, and mucinous carcinoma is common. The prognosis of CD-associated colon cancer and sporadic colon cancer is the same; however, the prognosis of CD-associated rectal cancer is clearly worse than that of sporadic rectal cancer. Early diagnosis is important to improve the prognosis of CD-associated rectal cancer, and it is necessary to establish a surveillance method for CD-associated cancer that combines colonoscopy, anesthetic proctoscopy, and imaging, as appropriate. The basic treatment for CD-related cancer is surgical resection; however, the criteria for selecting the surgical procedure are unclear, and there is no clear evidence for multidisciplinary perioperative treatment including chemotherapy and radiotherapy. Additionally, CD-related rectal and anal cancers have a higher local recurrence rate than that of sporadic rectal cancers; therefore, thorough local control is important. Furthermore, CD-related cancers have different epidemiologies in different regions; therefore, unique diagnostic and treatment strategies must be established for each region.

Clinical Characteristics and Outcomes of Small Bowel Neoplasms in Crohn's Disease: A Case-Control Study

Background

Patients with Crohn's disease (CD) who have ileal or any small bowel (SB) involvement are at increased risk of developing SB cancer. Due to the rarity of this complication of CD, we aimed to describe the clinical features, presentation, and of small bowel neoplasms (SBN) in patients with CD.

Methods

A case-control study was performed to include patients ≥18 years old with a diagnosis of CD with or without SBN at a single large referral center from January 1992 to May 2023. Patients were identified using bioinformatics and natural language processing tools, as well as anatomic pathology records. Two age- and sex-matched controls were identified for each case.

Results

In total, 54 patients with CD and SBN and 108 patients with CD without SBN were identified. Of the cases, most had ileal CD (55.6%) with stricturing (59.3%) phenotype. Median duration of CD prior to SBN diagnosis was 19.5 years. Nonpenetrating/nonstricturing behavior (odds ratio [OR], 9.23; 95% CI, 2.91-29.32; P = .0008) was significantly associated with an increased odds of SBN. History of tobacco use (OR, 0.27; 95% CI, 0.13-0.60; P = .0011) and IBD-associated colonic neoplasia (OR, 0.18; 95%, CI 0.4-0.85; P = .0303) were protective in development of SBN.

Conclusions

Nonpenetrating/nonstricturing CD appeared to raise SBN risk. History of tobacco use and colonic IBD-associated neoplasia are associated with reduced risk of SBN. Further studies with large sample sizes are needed to determine true incidence and risk factors associated with SBN in CD and assess potentially protective effects of early surgery.

Characteristics, clinical outcomes, and prognostic factors of colorectal cancer in patients with Crohn's disease: American versus Korean tertiary referral center perspectives

Background

Crohn's disease (CD) exhibits variability in colorectal cancer (CRC) incidence and prognostic factors due to diverse clinical and behavioral characteristics, presenting inconsistencies between Western and Eastern patients.

Objectives

This study compared clinical characteristics between CD patients with CRC from the US and Korean tertiary referral centers and defined the prognostic factors related to mortality.

Design

Retrospective study.

Methods

We reviewed the electronic medical records of 236 adult CD patients with colorectal adenocarcinoma evaluated at Mayo Clinic Rochester, Florida, or Arizona (N = 200) and Asan Medical Center in Korea (N = 36) between January 1989 and August 2022.

Results

Asan patients had a younger age, shorter CD duration, more colonic involvement (L2 plus L3), penetrating behavior, perianal fistula, and shorter biological treatment duration before CRC diagnosis than Mayo patients. Furthermore, despite significant differences in body mass index, smoking status, primary sclerosing cholangitis, immunomodulators, CRC diagnosis period, clinical presentation, CRC location, surgery, and some histopathological details between the two groups, overall survival was not statistically different (p value, 0.29, log-rank test). Advanced age (adjusted hazard ratio (aHR), 1.03 per year; 95% confidence interval (CI), 1.01-1.04; p value, <0.01), unresectable CRC (aHR, 5.02; 95% CI, 2.49-10.12; p value, <0.01), and advanced CRC stage (aHR, 1.45 per stage; 95% CI, 1.07-1.97; p value, 0.02) were significantly associated with increased risk of death. CD remission at CRC diagnosis (aHR, 0.26; 95% CI, 0.08-0.91; p value, 0.04), CRC diagnosis period of 2011-2022 (aHR relative to 1989-2000, 0.46; 95% CI, 0.25-0.87; p value, 0.02), and CRC diagnosis by surveillance (aHR, 0.56; 95% CI, 0.32-0.98; p value, 0.04) were significantly associated with decreased risk of death.

Conclusion

Notably, some clinical features of CD with CRC differed between Asan and Mayo patients; however, overall survival was not different. CD remission, CRC surveillance, and more recent diagnosis of CRC were associated with a reduced risk of death.

Small Bowel Cancer in Crohn's Disease

Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) that frequently affects the small bowel. Individuals diagnosed with CD are at increased risk of developing bowel cancer compared to the general population. Small bowel cancer is a rare but significant CD complication. Adenocarcinoma represents the most prevalent of these neoplasms, followed by neuroendocrine tumors and sarcomas. The primary risk factors identified are being of the male sex, disease duration, previous surgical intervention, perianal disease, and chronic inflammation. The precise etiology remains unclear. Another crucial issue concerns the role of immunomodulators and advanced therapies. By inhibiting inflammation, these therapies can reduce the risk of cancer, which is often initiated by the inflammation-dysplasia-adenocarcinoma sequence. In accordance with the most recent guidelines, it is not necessary to conduct surveillance in patients with small bowel cancer among CD patients, as it is considered a rare disease. Nevertheless, it is of significant importance for gastroenterologists to be aware of this potential CD complication, as well as the patients who are most at risk of developing it. The purpose of this review is to provide a comprehensive overview of CD-SBC, focusing on epidemiology, etiopathogenesis, risk factors, diagnosis, and the role of advanced therapies in CD-SBC.

Global patterns in the epidemiology, cancer risk, and surgical implications of inflammatory bowel disease

Inflammatory bowel disease (IBD), mainly including ulcerative colitis and Crohn's disease, imposes a huge medical and economic burden worldwide. Recently, the diagnosis, treatment, and surveillance of IBD have advanced rapidly, which has changed the epidemiology, cancer risk, and surgery risk of IBD. Here, we reviewed the recent literature on the epidemiology, IBD-related cancer, and IBD-related surgery. We created a choropleth map to show the worldwide incidence trend for Crohn's disease and ulcerative colitis. We also found that the cancer risk and surgery risk of IBD are declining and discussed some risk factors associated with them. Based on the recent trend, we proposed several suggestions and hoped to reduce the global burden of IBD as far as possible.

Possible poor prognosis in younger-onset Crohn's disease-associated anorectal cancer: A subanalysis of the Nationwide Japanese study

Background and aims

Crohn's disease (CD)-associated intestinal cancers are characterized by their high incidence, particularly at the anorectal site in the Japanese population. Accumulating evidence revealed that younger-onset sporadic colorectal cancer may exhibit unique biological features. To the best of our knowledge, few previous articles reported clinicopathological features in patients with CD-associated anorectal cancer (CDAAC). Therefore, we aimed to clarify the relationship between the younger onset of cancer and clinicopathological characteristics and prognosis, and the efficacy of cancer surveillance in patients with CDAAC.

Methods

CD patients who had been diagnosed with intestinal cancers from 1983 to 2020 were collected from 39 Japanese institutions in this study. Of 316 patients with CD-associated intestinal cancers, we analyzed 211 patients with CDAAC. We divided the patients into two groups according to the median age at cancer diagnosis (45 years old).

Results

Younger-onset CDAAC (YO-CDAAC) patients were significantly more likely to have a poor outcome than those with older-onset CDAAC (OO-CDAAC) in terms of both disease-free survival (DFS) (p = 0.0014) and overall survival (OS) (p = 0.023). Multivariate analysis showed that age under 45 years old at diagnosis of cancer was one of the independent factors for poor DFS and OS (hazard ratios: 2.15, 95% confidence interval: 1.09-4.26, p = 0.028, hazard ratios: 1.95, 95% confidence interval: 1.05-3.60, p = 0.033, respectively). Patients detected via surveillance showed significantly better DFS and OS rates than symptomatic patients in YO-CDAAC (p = 0.012 and 0.0031, respectively).

Conclusions

YO-CDAAC may have a poorer prognosis compared with OO-CDAAC. Surveillance could be important to improve cancer prognosis, especially in young CD patients with anorectal disease.

Management of Crohn's disease in Taiwan: consensus guideline of the Taiwan Society of Inflammatory Bowel Disease updated in 2023

Crohn's disease (CD) is a chronic, fluctuating inflammatory condition that primarily affects the gastrointestinal tract. Although the incidence of CD in Taiwan is lower than that in Western countries, the severity of CD presentation appears to be similar between Asia and the West. This observation indicates the urgency for devising revised guidelines tailored to the unique reimbursement system, and patient requirements in Taiwan. The core objectives of these updated guidelines include the updated treatment choices and the integration of the treat-to-target strategy into CD management, promoting the achievement of deep remission to mitigate complications and enhance the overall quality of life. Given the diversity in disease prevalence, severity, insurance policies, and access to medical treatments in Taiwan, a customized approach is imperative for formulating these guidelines. Such tailored strategies ensure that international standards are not only adapted but also optimized to local contexts. Since the inception of its initial guidelines in 2017, the Taiwan Society of Inflammatory Bowel Disease (TSIBD) has acknowledged the importance of continuous revisions for incorporating new therapeutic options and evolving disease management practices. The latest update leverages international standards and recent research findings focused on practical implementation within the Taiwanese healthcare system.

Multimodality imaging features of small bowel cancers complicating Crohn's disease: a pictorial review

Patients with Crohn's disease (CD) are at increased risk of developing small bowel cancer, since chronic inflammation may trigger the histopathological sequence that begins from low-grade dysplasia of the intestinal epithelium and may eventually lead to malignant transformation. Owing to their location in a portion of the gastrointestinal tract which is not easily accessible to conventional endoscopic techniques, the detection of CD-related small bowel cancers is still a clinical challenge. The radiological features of CD-related small bowel adenocarcinoma (SBA) in patients with CD have been described in some previous studies, including its appearance in both CT and MRI examinations. Radiological signs of active or fibrostenotic CD may be intermixed with those suggesting the presence of CD-related SBA. In CT studies, the most relevant findings consistent with malignant transformation are the presence of a stricture with irregular asymmetric thickening of small bowel walls, loss of mural stratification, and moderate enhancement after intravenous administration of iodinated contrast media, in association with enlarged adjacent mesenteric lymph nodes. Many of the CD-related SBA features that can be observed on CT imaging are similar to those detectable by MRI. This latter modality provides the additional value of the functional characterization of small bowel strictures, thereby helping to distinguish between inflammatory, fibrotic, and malignant stenosis in the setting of active CD. Positron Emission Tomography (PET)/CT enables the metabolic assessment of enlarged mesenteric lymph nodes, and PET/MRI fusion imaging can incorporate morphological, functional and metabolic information into a single set of imaging data, thus overcoming the limitations of the separate assessment of each individual modality. Owing to the low incidence and prevalence of this long-term complication of CD, we believe that a detailed multimodality pictorial essay on this topic, also including the PET-CT and fusion imaging documentation of some cases, would be useful to the medical literature.

Histological differentiation between sporadic and colitis-associated intestinal cancer in a nationwide study: A propensity-score-matched analysis

BACKGROUND AND AIM

Colitis-associated intestinal cancer (CAC) can develop in patients with inflammatory bowel disease; however, the malignant grade of CAC may differ from that of sporadic colorectal cancer (CRC). Therefore, we compared histological findings distinct from cancer stage between CAC and sporadic CRC to evaluate the features of CAC.

METHODS

We reviewed the clinical and histological data collected from a nationwide database in Japan between 1983 and 2020. Patient characteristics were compared to distinguish ulcerative colitis (UC), Crohn's disease (CD), and sporadic CRC. Comparisons were performed by using all collected data and propensity score-matched data.

RESULTS

A total of 1077 patients with UC-CAC, 297 with CD-CAC, and 136 927 with sporadic CRC were included. Although the prevalence of well or moderately differentiated adenocarcinoma (Tub1 and Tub2) decreased according to tumor progression for all diseases (P < 0.01), the prevalence of other histological findings, including signet ring cell carcinoma, mucinous carcinoma, poorly differentiated adenocarcinoma, or squamous cell carcinoma, was significantly higher in CAC than in sporadic CRC. Based on propensity score-matched data for 982 patients with UC and 268 with CD, the prevalence of histological findings other than Tub1 and Tub2 was also significantly higher in those with CAC. At pT4, mucinous carcinoma occurred at a significantly higher rate in patients with CD (45/86 [52.3%]) than in those with sporadic CRC (13/88 [14.8%]) (P < 0.01).

CONCLUSION

CAC, including early-stage CAC, has a higher malignant grade than sporadic CRC, and this difference increases in significance with tumor progression.

Current Perspectives on Small Bowel Tumors: Overview of Prevalence, Clinical Manifestations, and Treatment Approaches

Small bowel tumors (SBTs) constitute a rare yet increasingly recognized group of gastrointestinal neoplasms, accounting for less than 5% of all gastrointestinal cancers. Despite their infrequency, the incidence of SBTs has exhibited a notable upward trend, underscoring the importance of understanding these diverse and complex tumors. This review consolidates current knowledge on SBTs, encompassing epidemiology, risk factors, clinical manifestations, diagnostic advancements, and treatment modalities. Data from various sources are analyzed to present a comprehensive overview of the evolving landscape of SBTs. Our findings indicate that adenocarcinomas, carcinoid tumors, lymphomas, and gastrointestinal stromal tumors (GISTs) are the common SBTs. While adenocarcinoma and neuroendocrine tumors are the common types of SBTs in the West, GIST and lymphoma are more common in Asia. Common risk factors include genetic syndromes and inflammatory bowel diseases. There is variability in clinical presentations depending on the type of tumors. Although diagnostic challenges persist, advancements in imaging and endoscopic techniques have improved detection rates. Treatment strategies are evolving; surgical resection remains the mainstay for localized disease, augmented by systemic therapies and targeted agents for advanced stages. This review emphasizes the importance of early detection and individualized treatment approaches in improving outcomes for SBT patients. It addresses the need for ongoing research and innovation in managing these tumors.

Small Bowel Carcinoma in the Setting of Inflammatory Bowel Disease

Small bowel carcinomas are rare in the general population, but the incidence is increasing. Patients with inflammatory bowel diseases (IBDs) are at significantly higher risk of small bowel adenocarcinomas than their non-IBD counterparts, with Crohn's patients having at least a 12-fold increased risk and ulcerative colitis patients with a more controversial and modest 2-fold increased risk compared with the general population. IBD patients with small bowel carcinomas present with nonspecific symptoms that overlap with typical IBD symptoms, and this results in difficulty making a preoperative diagnosis. Cross-sectional imaging is rarely diagnostic, and most cancers are found incidentally at the time of surgery performed for an IBD indication. As such, most small bowel carcinomas are found at advanced stages and carry a poor prognosis. Oncologic surgical resection is the treatment of choice for patients with locoregional disease with little evidence available to guide adjuvant therapy. Patients with metastatic disease are treated with systemic chemotherapy, and surgery is reserved for palliation in this population. Prognosis is poor with few long-term survivors reported.

Appendiceal Mucinous Neoplasms and Inflammatory Bowel Disease: Systematic Review of the Literature

There is no clear evidence on the prevalence and clinical presentation of appendiceal mucinous neoplasm (AMN) among patients with inflammatory bowel disease (IBD), so a systematic review was performed to investigate the diagnosis, management and treatment of AMN in these patients. PubMed, Medline, Scopus and the Cochrane Library were searched for articles published up to September 2023. Twenty-three studies reporting data about 34 AMN patients were included. UC patients had a median age of 52 years and a median length of disease of 10 years; CD patients had a median age of 40.5 years and a median length of disease of 5 years. A pre-operative diagnosis was achieved in 44% of patients. Most patients were symptomatic (82.6%) and showed moderate-severe disease activity (61%). Surgical procedures were performed: laparoscopic appendectomy, ileocecal resection, right hemicolectomy and colectomy/proctocolectomy. Of the patients, 73.5% were diagnosed with low-grade mucinous neoplasm (LAMN) and nine with adenocarcinoma. Synchronous colorectal dysplasia/carcinoma was present in 23.5% of patients. IBD patients with long-standing disease should be routinely screened, not only for colorectal cancer but also for AMN, during gastro-enterologic follow-up. Laparoscopic appendectomy of unruptured LAMN as well as right hemicolectomy of non-metastatic adenocarcinoma are safe procedures in IBD patients.

Crohn's Disease-Associated Anorectal Cancer Has a Poor Prognosis With High Local Recurrence: A Subanalysis of the Nationwide Japanese Study

INTRODUCTION

Colorectal cancer (CRC) is one of the major life-threatening complications in patients with Crohn's disease (CD). Previous studies of CD-associated CRC (CD-CRC) have involved only small numbers of patients, and no large series have been reported from Asia. The aim of this study was to clarify the prognosis and clinicopathological features of CD-CRC compared with sporadic CRC.

METHODS

A large nationwide database was used to identify patients with CD-CRC (n = 233) and sporadic CRC (n = 129,783) over a 40-year period, from 1980 to 2020. Five-year overall survival (OS), recurrence-free survival (RFS), and clinicopathological characteristics were investigated. The prognosis of CD-CRC was further evaluated in groups divided by colon cancer and anorectal cancer (RC). Multivariable Cox regression analysis was used to adjust for confounding by unbalanced covariables.

RESULTS

Compared with sporadic cases, patients with CD-CRC were younger; more often had RC, multiple lesions, and mucinous adenocarcinoma; and had lower R0 resection rates. Five-year OS was worse for CD-CRC than for sporadic CRC (53.99% vs 71.17%, P < 0.001). Multivariable Cox regression analysis revealed that CD was associated with significantly poorer survival (hazard ratio 2.36, 95% confidence interval: 1.54-3.62, P < 0.0001). Evaluation by tumor location showed significantly worse 5-year OS and RFS of CD-RC compared with sporadic RC. Recurrence was identified in 39.57% of CD-RC cases and was mostly local.

DISCUSSION

Poor prognosis of CD-CRC is attributable primarily to RC and high local recurrence. Local control is indispensable to improving prognosis.

Perioperative optimization of Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disease mainly affecting the gastrointestinal tract. With the increased availability of modalities in the last two decades, the treatment of CD has advanced remarkably. Although medical treatment is the mainstay of therapy, most patients require surgery during the course of their illness, especially those who experience complications. Nutritional optimization and ERAS implementation are crucial for patients with CD who require surgical intervention to reduce postoperative complications. The increased surgical risk was found to be associated with the use of corticosteroids, but the association of surgical risk with immunomodulators, biologic therapy, such as anti-TNF mediations, anti-integrin medications, and anti-IL 12/23 was low in certainty. Decisions about preoperative medication must be made on an individual case-dependent basis. Preoperative imaging studies can assist in the planning of appropriate surgical strategies and approaches. However, patients must be informed of any alterations to their treatment. In summary, the management of perioperative medications and surgery-related decision-making should be individualized and patient-centered based on a multidisciplinary approach.

Role of adherent invasive Escherichia coli in pathogenesis of inflammatory bowel disease

Gut microbiota imbalances play an important role in inflammatory bowel disease (IBD), but no single pathogenic microorganism critical to IBD that is specific to the IBD terminal ileum mucosa or can invade intestinal epithelial cells has been found. Invasive Escherichia coli (E. coli) adhesion to macrophages is considered to be closely related to the pathogenesis of inflammatory bowel disease. Further study of the specific biological characteristics of adherent invasive E. coli (AIEC) may contribute to a further understanding of IBD pathogenesis. This review explores the relationship between AIEC and the intestinal immune system, discusses the prevalence and relevance of AIEC in Crohn's disease and ulcerative colitis patients, and describes the relationship between AIEC and the disease site, activity, and postoperative recurrence. Finally, we highlight potential therapeutic strategies to attenuate AIEC colonization in the intestinal mucosa, including the use of phage therapy, antibiotics, and anti-adhesion molecules. These strategies may open up new avenues for the prevention and treatment of IBD in the future.

Risk of Cancer in Inflammatory Bowel Diseases: Umbrella Review and Reanalysis of Meta-analyses

BACKGROUND & AIMS

To summarize the epidemiologic evidence and assess the validity of claimed associations of inflammatory bowel diseases (IBDs) with overall and site-specific cancer risk.

METHODS

We systematically searched PubMed, Embase, and Scopus from inception to May 10, 2021, to identify and comprehensively reanalyze the data of meta-analyses on associations between IBDs (ie, Crohn's disease [CD] and ulcerative colitis [UC]) and subsequent risk of cancer. The strength of epidemiologic evidence was graded as high, moderate, or weak, by applying prespecified criteria that included the random effects estimate, its 95% confidence interval, and P value, estimates of heterogeneity, small-study effects, and robustness to unmeasured confounding.

RESULTS

This study critically appraised 277 estimates derived from 24 published meta-analyses and our own meta-analyses. The association between pediatric-onset IBDs and overall risk of cancer showed high epidemiologic evidence. Twenty associations (15 cancer types) demonstrated moderate evidence: any cancer (pediatric-onset UC), mouth to terminal ileum (CD), small bowel (CD/UC), colon (CD), rectum (CD/UC), colon-rectum (IBDs, pediatric-onset CD/UC), bile ducts and liver (CD/UC), liver (CD), intrahepatic cholangiocarcinoma (IBDs), bile ducts (CD), skin (CD), squamous cell carcinoma of the skin (CD), nonmelanoma skin cancer (UC), kidney (CD), and thyroid cancer (IBDs). Another 40 associations (23 cancer types) showed statistical significance; however, our confidence in these effect estimates was weak. No statistical significance was found regarding further 47 associations.

CONCLUSIONS

Associations between IBDs and different types of malignancy showed varying levels of evidence and magnitude of risk. Further primary research investigating the impact of a consistent set of risk factors that are known to affect cancer risk is warranted.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021254996.

Intestinal Cancer and Dysplasia in Crohn's Disease

Crohn's disease is associated with an increased risk of adenocarcinoma of the involved portions of the small bowel and colorectum and has similar risk factors to those described in ulcerative colitis, most significantly, extent of bowel involvement, PSC, and duration of unresected disease. Prevention strategies include risk stratification and secondary prevention with colonoscopic screening and surveillance to identify dysplasia or early-stage cancers, with surgery when needed. There is emerging information to suggest that control of inflammation may provide primary prevention of neoplasia, but further studies are required to test this strategy.

Evidence-based clinical practice guidelines for inflammatory bowel disease 2020

Inflammatory bowel disease (IBD) is a general term for chronic or remitting/relapsing inflammatory diseases of the intestinal tract and generally refers to ulcerative colitis (UC) and Crohn's disease (CD). Since 1950, the number of patients with IBD in Japan has been increasing. The etiology of IBD remains unclear; however, recent research data indicate that the pathophysiology of IBD involves abnormalities in disease susceptibility genes, environmental factors and intestinal bacteria. The elucidation of the mechanism of IBD has facilitated therapeutic development. UC and CD display heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management depends on the understanding and tailoring of evidence-based interventions by physicians. In 2020, seventeen IBD experts of the Japanese Society of Gastroenterology revised the previous guidelines for IBD management published in 2016. This English version was produced and modified based on the existing updated guidelines in Japanese. The Clinical Questions (CQs) of the previous guidelines were completely revised and categorized as follows: Background Questions (BQs), CQs, and Future Research Questions (FRQs). The guideline was composed of a total of 69 questions: 39 BQs, 15 CQs, and 15 FRQs. The overall quality of the evidence for each CQ was determined by assessing it with reference to the Grading of Recommendations Assessment, Development and Evaluation approach, and the strength of the recommendation was determined by the Delphi consensus process. Comprehensive up-to-date guidance for on-site physicians is provided regarding indications for proceeding with the diagnosis and treatment.