Inflammatory bowel disease increases the risk of hepatobiliary pancreatic cancer: A two-sample Mendelian randomization analysis of European and East Asian populations

Novel molecular mechanisms of immune evasion in hepatocellular carcinoma: NSUN2-mediated increase of SOAT2 RNA methylation

BACKGROUND

Hepatocellular carcinoma (HCC) is a deadly malignancy known for its ability to evade immune surveillance. NOP2/Sun RNA methyltransferase family member 2 (NSUN2), an RNA methyltransferase involved in carcinogenesis, has been associated with immune evasion and energy metabolism reprogramming. This study aimed to examine the molecular mechanisms underlying the involvement of NSUN2 in immune evasion and metabolic reprogramming of HCC.

METHODS

Single-cell transcriptomic sequencing was applied to examine cellular composition changes, particularly immune cell dynamics, in HCC and adjacent normal tissues. Bulk RNA-seq and proteomics identified key genes and proteins. Methylation sequencing and methylated RNA immunoprecipitation (MeRIP) were carried out to characterize the role of NSUN2 in 5-methylcytosine (m5C) modification of sterol O-acyltransferase 2 (SOAT2). Clinical samples from 30 HCC patients were analyzed using reverse transcription-quantitative polymerase chain reaction and Western blotting. Gene expression was manipulated using CRISPR/Cas9 and lentiviral vectors. In vitro co-culture models and metabolomics were used to study HCC cell-T cell interactions, energy metabolism, and immune evasion. Tumor growth in an orthotopic mouse model was monitored by bioluminescence imaging, with subsequent measurements of tumor weight, volume, and immunohistochemical staining.

RESULTS

Single-cell transcriptomic analysis identified a marked increase in malignant cells in HCC tissues. Cell communication analysis indicated that tumor cells might promote cancer progression by evading immune clearance. Multi-omics analyses identified NSUN2 as a key regulator in HCC development. MeRIP confirmed that NSUN2 facilitated the m5C modification of SOAT2. Analysis of human HCC tissue samples demonstrated pronounced upregulation of NSUN2 and SOAT2, along with elevated m5C levels in HCC tissues. In vitro experiments uncovered that NSUN2 augmented the reprogramming of energy metabolism and repressed the activity and cytotoxicity of CD8+ T cells, contributing to immune evasion. In vivo studies further substantiated the role of NSUN2 in fostering immune evasion and tumor formation of HCC by modulating the m5C modification of SOAT2.

CONCLUSIONS

The findings highlight the critical role of NSUN2 in driving HCC progression through the regulation of m5C modification on SOAT2. These findings present potential molecular markers for HCC diagnosis and therapeutic targets for its treatment.

Development and Validation of the Predictive and Prognostic ChemoResist Signature in Resected Pancreatic Ductal Adenocarcinoma: Multicohort Study

OBJECTIVE

To develop and validate a signature to precisely predict prognosis in pancreatic ductal adenocarcinoma (PDAC) undergoing resection and adjuvant chemotherapy.

BACKGROUND

PDAC is largely heterogeneous and responds discrepantly to treatment.

METHODS

A total of 551 consecutive patients with PDAC from 3 different cohorts of tertiary centers were initially enrolled. Genetic events of the 4 most commonly mutated genes in PDAC and expressions of 12 PI3K/AKT/mammalian target of rapamycin (mTOR) pathway markers were examined. A 9-feature signature for the prediction of chemotherapy benefits was constructed in the training cohort using the least absolute shrinkage and selection operator Cox regression model and validated in 2 independent cohorts.

RESULTS

Utilizing the least absolute shrinkage and selection operator model, a predictive and prognostic signature, named ChemoResist, was established based on KRAS single nucleotide variant (SNV), phosphatase and tensin homologue (PTEN), and mTOR expressions, and 6 clinicopathologic features. Significant differences in survival were observed between high and low-ChemoResist patients receiving chemotherapy in both the training [median overall survival (OS), 17 vs 42 months, P < 0.001; median disease-free survival (DFS), 10 vs 23 months, P < 0.001] and validation cohorts (median OS, 18 vs 35 months, P = 0.034; median DFS, 11 vs 20 months, P = 0.028). The ChemoResist classifier also significantly differentiated patient survival in whole patients regardless of chemotherapy. Multivariable-adjusted analysis substantiated the ChemoResist signature as an independent predictive and prognostic factor. For predicting 2-year OS, the ChemoResist classifier had significantly higher areas under the curve than TNM stage (0.788 vs 0.636, P < 0.001), other clinicopathologic characteristics (0.505-0.668), and single molecular markers (0.507-0.591) in the training cohort. Furthermore, patients with low ChemoResist scores exhibited a more favorable response to adjuvant chemotherapy compared with those with high ChemoResist scores (hazard ratio for OS: training, 0.22 vs 0.57; validation, 0.26 vs 0.50; hazard ratio for DFS: training, 0.35 vs 0.54; validation, 0.18 vs 0.59). The ChemoResist signature was further validated in the total cohort undergoing R0 resection.

CONCLUSIONS

The ChemoResist signature could precisely predict survival in PDAC undergoing resection and chemotherapy, and its predictive value surpassed the TNM stage and other clinicopathologic factors. Moreover, the ChemoResist classifier could assist with identifying patients who would more likely benefit from adjuvant chemotherapy.

The mediating role of primary sclerosing cholangitis in the association between ulcerative colitis and hepatobiliary cancer investigated through Mendelian randomization

This study explored the causal relationships among primary sclerosing cholangitis (PSC), ulcerative colitis (UC), and hepatobiliary cancer (HBC) by using bidirectional two-sample, two-step Mendelian randomization (MR) analysis. Genetic variants associated with PSC and UC from the FinnGen research database were used for instrumental variable-based analyses. Mediation analyses were conducted to examine the role of PSC and UC in HBC risk. The findings revealed a causal effect of genetic predisposition to UC on PSC risk (inverse-variance-weighted [IVW] analysis odds ratio [OR] 1.145, p < 0.001), whereas no reverse causality was observed. Although UC showed no direct causal effect on HBC risk, genetic susceptibility to PSC significantly increased the risk of HBC (IVW analysis OR = 1.855, p < 0.001). Mediation analysis further identified PSC as a significant mediator amplifying the causal effect of UC on HBC risk (effect size = 0.083). These results established a causal link between genetic susceptibility to UC and increased risk of PSC, and highlighted the critical role of PSC in mediating the impact of UC on HBC risk.

Causal Relationship and Potential Common Pathogenic Mechanisms Between Alopecia Areata and Related Cancer

Objective

Alopecia areata (AA) is an autoimmune skin disease. Observational studies have reported an association between AA and cancer. However, the causal relationship between AA and cancer has not been reported. We employed a two-sample Mendelian randomization (MR) study to assess the causality between AA and 17 subtypes of cancers.

Methods

We employed a two-sample Mendelian randomization (MR) study to assess the causality between AA and 17 subtypes of cancers. AA and cancers' association genome-wide association study (GWAS) data were collected. The inverse variance weighted (IVW) method was utilized as the principal method in our Mendelian randomization (MR) study, with additional use of the MR-Egger, weighted median, simple mode, and weighted mode methods. After that, we explored the underlying biological mechanisms by Bioinformatic Analysis.

Results

According to our MR analysis, AA has a causal relationship with hepatic bile duct cancer (HBDC, (odds ratio [OR] = 0.944, 95% confidence interval [CI] = 0.896-0.994, P-value = 0.030) and colorectal cancer (CRC, OR = 0.981, 95% CI = 0.963-0.999, P-value = 0.046). AA could decrease the risk of HBDC and CRC. No causal link between AA and other subtypes of cancers was observed. No heterogeneity or pleiotropy was observed. Furthermore, disease-related genes were obtained, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis results showed that the set of genes associated with immunity-inflammatory signaling pathway.

Conclusion

This study provided new evidence of the relationship between AA with HBDC and CRC. AA may play a protective role in both HBDC and CRC progression. This could provide newer avenues for research in search of treatment for HBDC and CRC.

The Causal Relationship between Gut Microbiota and Atrial Fibrillation: A Two-Sample Mendelian Randomization Study

BACKGROUND

Previous studies have adequately characterized the gut microbiota (GM) in atrial fibrillation (AF). Nevertheless, the precise causality between GM and AF remains elusive.

OBJECTIVES

This study utilized public data from genome-wide association studies to explore the causality between GM and AF.

METHODS

In the first of two rounds of Mendelian randomization (MR) analysis, the instrumental variables (IVs) comprised single nucleotide polymorphisms (SNPs) that fell below the genome-wide statistical significance threshold (5 × 10-8). To attain a more comprehensive and inclusive conclusion, we further selected SNPs falling below the locus-wide significance level (1 × 10-5) as IVs for the second group. The MR analysis considered the statistically significant causal effect between the specific GM and AF when p < 0.05. Furthermore, in sensitivity analysis, p > 0.05 indicated no heterogeneity and pleiotropy.

RESULTS

At the locus-wide significance threshold, the findings demonstrated a causal impact of GM on AF risk. The inverse variance weighting method indicated that Actinobacteria, Firmicutes, Alloprevotella, Bifidobacterium, Blautia, Eggerthella, Howardella, Ruminococcaceae UCG004, and Ruminococcus1 were negatively correlated with AF, while Pasteurellales, Pasteurellaceae, Oxalobacter, Ruminiclostridium5, and Turicibacter were positively correlated. Furthermore, at the genome-wide significance threshold, Actinobacteria, Bifidobacteriaceae, and Bifidobacterium were protective factors for the risk of developing AF, whereas Oxalobacteraceae and Erysipelatoclostridium were risk factors for AF. However, sensitivity analyses showed heterogeneity or horizontal pleiotropy within the outcomes for Actinobacteria, Howardella, Oxalobacter, and Firmicutes.

CONCLUSIONS

This study provides evidence for the existence of both favorable and unfavorable causality of GM on AF risk.

Classification of long-term disease patterns in inflammatory bowel disease and analysis of their associations with adverse health events

BACKGROUND

With existing researches identifying an increased rate of long-term conditions (LTCs) among Inflammatory Bowel Disease (IBD) patients, yet there is a lack of exploration into the patterns of comorbidity and prognostic rates for IBD patients with multiple morbidities.

METHODS

The study included 8,305 participants who self-reported having IBD, comprising ulcerative colitis (UC) and Crohn's disease (CD). Latent class analysis (LCA) was utilized to create optimal categories of LTC combinations for UC and CD patients with additional long-term conditions. Using Cox proportional hazards models, we compared the all-cause mortality rates over a 16-year follow-up among UC and CD patients within different LTC categories, both without LTCs and with the addition of one LTC, the probability of major adverse cardiovascular events (MACE), and the rates of IBD-related surgeries.

RESULTS

A total of 5,617 participants reported having two or more LTCs, with the LCA method identifying three prevalence categories among CD patients, and four prevalence categories among UC patients. The highest mortality rate among CD patients was found in category 3: (HR 1.789, 95% CI (1.439-2.224)), and the highest rates of MACE were also in category 3: (HR 11.432, 95% CI (9.332-14.005)), with hypertension being the distinguishing characteristic of this category, and the highest rates of IBD-related surgeries being associated with pain in category 1: (HR 1.217, 95% CI (0.983-1.506)). Among UC patients, the highest mortality rate was in category 3: (HR 2.221, 95% CI (1.837-2.684)), with the highest MACE rates found in category 3: (HR 6.422, 95% CI (5.659-7.288)), and the highest rates of IBD-related surgeries being associated with pain, also in category 3: (HR 1.218, 95% CI (1.041-1.425)).

CONCLUSION

The rates of adverse health outcomes in IBD patients is closely associated with multimorbidity patterns, underscoring the need to fully consider multimorbidity patterns in the assessment, management, and treatment strategies for IBD.

Bidirectional two-sample Mendelian randomization analysis investigates causal associations between cathepsins and inflammatory bowel disease

Background

Cathepsins, key regulators of the pathology of gastrointestinal disorders such as inflammatory bowel disease (IBD), are a target protease that has attracted much attention in recent years. IBD is a chronic and relapsing inflammatory disorder of the gut. Traditional studies have shown a correlation between cathepsin and the risk of IBD, while the causal relationship remains unclear.

Methods

This study utilized Mendelian randomization techniques to evaluate the causal relationships between eleven cathepsins and the subtypes of IBD, such as ulcerative colitis (UC) and Crohn's disease (CD). We also performed a series of sensitivity analyses to validate the primary Mendelian randomization (MR) results, including Cochran's Q test, the MR-PRESSO global test, and the MR pleiotropy test.

Results

The forward MR analyses showed no significant association between cathepsins and IBD. Reverse Mendelian randomization analyses suggested that UC might lead to elevated cathepsin G levels [inverse-variance weighted (IVW): p = 0.038, b = 9.966], and CD might cause a decrease in cathepsin B levels [IVW: p = 0.002, b = -10.525] and cathepsin L1 levels [IVW: p = 0.045, b = -4.742].

Conclusions

Our findings offer novel and comprehensive evidence on the impact of UC or CD on cathepsins, potentially providing valuable insights into the treatment and prognosis of IBD.

Unraveling the causal link: fatty acids and inflammatory bowel disease

Background

Previous observational studies have revealed the strong relationship between fatty acids (FA) and inflammatory bowel disease (IBD). Nonetheless, due to the inherent limitations of retrospective research, the causality between the two has not been clearly established.

Methods

Genetic variants associated with the 17 FA indicators were derived from genome-wide association studies. Summary statistics for the discovery cohort and testing cohort for IBD, including ulcerative colitis (UC) and Crohn's disease (CD), were available from IIBDGC and FinnGen, respectively. Bidirectional MR analysis and sensitivity analysis with multiple measures were applied to comprehensively investigate the causal link between FA and IBD.

Results

Combining the results of various MR methods, the validation of testing cohort, and the merging of meta-analysis, we demonstrated that genetically predicted Omega-3 FA levels, Ratio of Omega-3 FA to total FA, Docosahexaenoic acid (DHA) levels, and Ratio of DHA to total FA reduced the risk of IBD, UC, and CD. Meanwhile, multivariate MR suggested that the risk effects of Omega-3 FA and DHA for UC and CD were mainly affected by Saturated FA and Monounsaturated fatty acid (MUFA). Furthermore, although there was the causal association between Ratio of MUFA to total FA as well as Ratio of Polyunsaturated fatty acid (PUFA) to MUFA and CD, sensitivity analysis prompted that the findings were not robust. None of the above results had a reverse causal effect.

Conclusion

This MR investigation provided evidence of causality between diverse FA and IBD. These findings offered new insights into the treatment and prevention of IBD.

Novel insights into rosacea's role in cancer risk: A Mendelian randomization approach

BACKGROUND

Chronic inflammation has been shown to promote cancer progression. Rosacea is indeed a long-term inflammatory skin condition and had been reported to link with increased risk for several types of malignancies, but evidence for causality is lacking.

OBJECTIVES

To systematically estimate the causal relationship between rosacea and several types of cancer, including cutaneous malignant melanoma (CMM), cutaneous squamous cell carcinoma (cSCC), basal cell carcinoma (BCC), actinic keratosis (AK), thyroid cancer, breast cancer, glioma and hepatic cancer, as well as explore the potential underlying pathogenesis.

METHODS

We conducted a bidirectional two-sample Mendelian randomization study to probe the potential causal relationships between rosacea and several types of cancer. Instrumental variables were established using genome-wide significant single nucleotide polymorphisms associated with rosacea and cancers. The assessment of causality was carried out through multiple methods, and the robustness of the results was evaluated via sensitivity analyses.

RESULTS

There was no significant indication of causal effects of rosacea on CMM (pivw = 0.71), cSCC (pivw = 0.45), BCC (pivw = 0.90), AK (pivw = 0.73), thyroid cancer (pivw = 0.59), glioma (pivw = 0.15), and hepatic cancer (pivw = 0.07), but the genetic risk of rosacea was associated with an increased susceptibility to human epidermal growth factor receptor (HER)-negative malignant neoplasm of breast (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.02-1.18; pivw = 0.01). TANK (TRAF family member associated nuclear factor kappa B (NFKB) activator) was identified as a common protective gene for both rosacea (OR, 0.90; 95% CI, 0.82-0.99; pivw = 0.048) and HER-negative malignant neoplasm of the breast (OR, 0.86; 95% CI, 0.75-0.98; pivw = 0.032), which was primarily enriched in the negative regulation of NF-κB signal transduction and may contribute to the genetic links between rosacea and this subtype of breast cancer.

CONCLUSIONS

Our findings provide suggestive evidence for causal links between rosacea and HER-negative malignant neoplasm of the breast risk.

Meta-analysis: Risk of pancreatic cancer in patients with inflammatory bowel disease

BACKGROUND

Studies exploring the association between inflammatory bowel disease (IBD) and pancreatic cancer have reported inconsistent results.

AIMS

To provide a comprehensive overview of the risk of pancreatic cancer development in patients with IBD.

METHODS

We searched Embase, PubMed, Scopus and ProQuest from inception to 31 October 2023. We included population-based cohort studies examining the risk of incident pancreatic cancer in adult patients with IBD compared to the non-IBD population. We also retrieved Mendelian randomisation (MR) studies investigating the relationship of IBD with pancreatic cancer risk. We conducted random-effects meta-analyses and provided pooled relative risks (RRs) with 95% confidence intervals (CIs).

RESULTS

We included 13 studies. Among 11 cohort studies, the risk of developing pancreatic cancer increased by 79% in patients with IBD (RR = 1.79 [95% CI: 1.16-2.75]; I2 = 95.7%). Patients either with Crohn's disease (RR = 1.42 [95% CI: 1.24-1.63]) or ulcerative colitis (RR = 1.50 [95% CI: 1.17-1.92]) had increased risk (p for interaction = 0.72). The annual incidence of pancreatic cancer potentially attributable to IBD increased by 55 cases (95% CI: 17-103) per million. Two MR studies demonstrated that genetic liability to IBD was associated with an increased risk of pancreatic cancer.

CONCLUSIONS

Our results suggest a moderate increase in the risk of pancreatic cancer in patients with IBD, which may be further heightened by genetic predisposition to IBD. The increased risk of pancreatic cancer is probably similar in Crohn's disease and ulcerative colitis.

Association between inflammatory bowel disease and cancer risk: evidence triangulation from genetic correlation, Mendelian randomization, and colocalization analyses across East Asian and European populations

BACKGROUND

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), has been associated with several cancer risks in observational studies, but the observed associations have been inconsistent and may face the bias of confounding and reverse causality. The potential causal relationships between IBD and the risk of cancers remain largely unclear.

METHODS

We performed genome-wide linkage disequilibrium score regression (LDSC), standard two-sample Mendelian randomization (MR), and colocalization analyses using summary genome-wide association study (GWAS) data across East Asian and European populations to evaluate the causal relationships between IBD and cancers. Sensitivity analyses for the MR approach were additionally performed to explore the stability of the results.

RESULTS

There were no significant genetic correlations between IBD, CD, or UC and cancers (all P values > 0.05) in East Asian or European populations. According to the main MR analysis, no significant causal relationship was observed between IBD and cancers in the East Asian population. There were significant associations between CD and ovarian cancer (odds ratio [OR] = 0.898, 95% CI = 0.844-0.955) and between UC and nonmelanoma skin cancer (OR = 1.002, 95% CI = 1.000-1.004, P = 0.019) in the European population. The multivariable MR analysis did not find any of the above significant associations. There was no shared causal variant to prove the associations of IBD, CD, or UC with cancers in East Asian or European populations using colocalization analysis.

CONCLUSIONS

We did not provide robust genetic evidence of causal associations between IBD and cancer risk. Exposure to IBD might not independently contribute to the risk of cancers, and the increased risk of cancers observed in observational studies might be attributed to factors accompanying the diagnosis of IBD.

Causal effects of gut microbiota in the development of lung cancer and its histological subtypes: A Mendelian randomization study

BACKGROUND

Numerous studies have characterized the gut microbiome (GM) in lung cancer (LC). Yet, the causality between GM and LC and its subtypes remain uncharacterized.

METHODS

Two-sample Mendelian randomization (MR) was designed to investigate the causal relationship between the GM and LC and its subtypes, using publicly available summary data of genome-wide association studies. The researchers ran two groups of MR analyses, including the genome-wide statistical significance threshold (5 × 10-8 ) and the locus-wide significance level (1 × 10-5 ).

RESULTS

Using MR analysis, we ascertained 42 groups of GM that are intimately linked to LC and its subtypes at the locus-wide significance level. Of the 42 groups, 12 were in LC, nine in non-small cell lung cancer (NSCLC), six in small cell lung cancer (SCLC), two in lung adenocarcinomas, and 13 in lung squamous carcinomas. After false discovery rate correction, we still found a remarkable causal interaction between the Eubacterium ruminantium group and SCLC. Moreover, five groups of GM closely linked to LC and its subtypes were recognised at the genome-wide statistical significance threshold. This finding included one group each in LC, NSCLC and SCLC, two groups in lung adenocarcinoma and none in lung squamous carcinoma. None of the foregoing findings were heterogeneous or horizontal pleiotropy. Reverse MR revealed that genetic susceptibility to LC and its subtypes caused significant changes in three groups of GM.

CONCLUSION

Our findings substantiate the causality between GM and LC and its subtypes. This study offers fresh insights into the function of GM in mediating the progression of LC.

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.

An inverse causal relationship between serum 25-hydroxyvitamin D levels and pulmonary hypertension: A two-sample Mendelian randomization study

Observational studies have confirmed that 25-hydroxyvitamin D (25(OH)D) is associated with pulmonary hypertension (PH), but the causal association between each other is unclear. Therefore, Mendelian randomization (MR) method was performed to validate the causal association between PH and serum 25(OH)D levels. The summary data for 25(OH)D and PH were from the National Human Genome Research Institute-European Bioinformatics Institute. Catalog of human genome-wide association studies and FinnGen biobank consortium. MR analysis was utilized to explore the potential causal association between PH and 25(OH)D. To evaluate this association, inverse variance weighting was considered as the primary method. Cochran's Q test, MR-Egger intercept test, and "leave-one-out" sensitivity analyses were utilized to control the pleiotropy and heterogeneity in the study. Two-sample MR analysis revealed an inverse causal relationship between 25(OH)D and PH (odds ratio: 0.376, 95% confidence interval: 0.162-0.876, p = 2.334 × 10-2). There was no significant heterogeneity and pleiotropy. The present study confirmed the inverse causal relationship between 25(OH)D and PH. This pathway may provide another treatment pathway in PH. Further studies to elucidate this pathway is indicated.

Genetically Predicted Causal Effects of Gut Microbiota and Gut Metabolites on Digestive Tract Cancer: A Two-Sample Mendelian Randomization Analysis

Background

Evidence from numerous observational studies and clinical trials has linked gut microbiota and metabolites to digestive tract cancer. However, the causal effect between these factors remains uncertain.

Methods

Data for this study were obtained from the MiBioGen, TwinsUK Registry, and FinnGen (version R8). Two-sample Mendelian randomization analysis with inverse variance weighting method was primarily used, and the results were validated by heterogeneity analysis, pleiotropy test, and sensitivity analysis.

Results

At P < 5 × 10-8, our analysis identified four gut microbiotas as risk factors for digestive tract cancer and six as risk factors for colorectal cancer. Conversely, one gut microbiota exhibited protection against bile duct cancer, and two showed protective effects against stomach cancer. At P < 1 × 10-5, our investigation revealed five, six, three, eight, eight, and eight gut microbiotas as risk factors for esophageal, stomach, bile duct, liver, pancreatic, and colorectal cancers, respectively. In contrast, four, two, eight, two, two, and five gut microbiotas exhibited protective effects against these cancers. Additionally, GABA, a metabolite of gut microbiota, displayed a significant protective effect against colorectal cancer.

Conclusion

In conclusion, specific gut microbiota and metabolites play roles as risk factors or protective factors for digestive tract cancer, and a causal relationship between them has been established, offering novel insights into gut microbiota-mediated cancer development.