Risk of renal cancer in patients with inflammatory bowel disease: A pooled analysis of population-based studies

Overcoming cancer risk in inflammatory bowel disease: new insights into preventive strategies and pathogenesis mechanisms including interactions of immune cells, cancer signaling pathways, and gut microbiota

Inflammatory bowel disease (IBD), characterized primarily by gastrointestinal inflammation, predominantly manifests as Crohn's disease (CD) and ulcerative colitis (UC). It is acknowledged that Inflammation plays a significant role in cancer development and patients with IBD have an increased risk of various cancers. The progression from inflammation to carcinogenesis in IBD is a result of the interplay between immune cells, gut microbiota, and carcinogenic signaling pathways in epithelial cells. Long-term chronic inflammation can lead to the accumulation of mutations in epithelial cells and the abnormal activation of carcinogenic signaling pathways. Furthermore, Immune cells play a pivotal role in both the acute and chronic phases of IBD, contributing to the transformation from inflammation to tumorigenesis. And patients with IBD frequently exhibit dysbiosis of the intestinal microbiome. Disruption of the gut microbiota and subsequent immune dysregulation are central to the pathogenesis of both IBD and colitis associated colorectal cancer (CAC). The proactive management of inflammation combined with regular endoscopic and tumor screenings represents the most direct and effective strategy to prevent the IBD-associated cancer.

Two-sample Mendelian randomization study reveals no causal relationship between inflammatory bowel disease and urological cancers

Background: The relationship between inflammatory bowel disease (IBD) and urological cancers has been identified in epidemiological and observational studies, while the causality remains uncertain. We examined whether IBD is causally associated with urological cancers in a Mendelian randomization (MR) study. Methods: The causal relationship between IBD, its main subtypes, and urological cancers was investigated using genome-wide association study data. To obtain more reliable conclusions, all outcomes were divided into training and validation sets. Eligible single-nucleotide polymorphisms were selected as instrumental variables based on MR analysis assumptions. The inverse variance-weighted (IVW) method was employed as the main method along with four other complementary methods. Results: In this two-sample MR study, no genetic evidence for the causal effect of IBD on urological cancers was found in either the training or validation sets using the IVW method. Similarly, we did not observe any significant association between Crohn's disease or ulcerative colitis and urological cancers. The results of the other methods are in accordance with those obtained using the IVW method. Conclusion: In this study, we confirmed that IBD is not a causal genetic risk factor for urological cancer in a European population.

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.

Risk of malignancy in patients with inflammatory bowel disease: a population-based cohort study from China

Carcinogenesis is one of major complications for patients with inflammatory bowel disease (IBD) and causes poor prognosis. We aimed to describe cancer incidence in Chinese IBD cohort compared with general population-based cancer registration data and further explore associated risk factors for cancer occurrence in IBD patients. IBD inpatients from January 1998 to January 2018 were included in this study. Patients were followed up from date of IBD diagnosis until either the date of first cancer diagnosis or January 2019. Standardized incidence ratios (SIRs) of overall cancer and site-specific cancers were calculated. A total of 869 UC and 516 CD patients were finally included with median follow-up time of 7 and 5 years respectively. 53 cases developed malignancies. After standardization by age and gender, standardized incidence ratio (SIR) of total cancer occurrence in IBD patients was 1.77 (95%CI, 1.33-2.32). As for UC, digestive cancers (SIR 3.75; 95%CI, 2.29-5.80), thyroid cancer (SIR 10.34; 95%CI, 4.72-19.64) and hematological malignancies (SIR 6.25; 95%CI, 1.68-16.00) had the highest incidence, which were prominent in young and middle-aged patients. Use of steroids, immunosuppressants or infliximab did not present higher risk of malignancies in UC patients. There were no significant difference in cancer risk between CD patients and general population. In conclusion, the increased risks of multiple cancers are particularly prominent in Chinese UC patients and these findings can provide more targeted guidance for cancer monitoring in Chinese IBD patients.