Irritable Bowel Syndrome Is Not Associated with an Increased Risk of Polyps and Colorectal Cancer: A Systematic Review and Meta-Analysis.

Theodoros Vichos, Ali Rezaie, Petros Vichos, Brooks Cash, Mark Pimentel

Journal: Digestive diseases and sciences 2023;68(6):2585-2596

PMID: 36871131

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Plain Language Summary

Colorectal cancer (CRC) is one of the most common cancers and adenomatous colorectal polyps (CRP) are a risk factor for developing CRC. The potential role of functional disturbances seen in irritable bowel syndrome (IBS) for the development of CRC are not yet clear. The aim of this systematic review and meta-analysis was to evaluate the occurrence of CRC and CRP in IBS patients. 14 cohort studies with a total of 654,764 IBS patients and 2,277,195 controls and six cross-sectional studies with 26,641 IBS patients and 87,803 controls were included in the review. Based on the pooled data from 5 cross-sectional studies, IBS patients had a significantly lower occurrence of CRP (by 71%). CRC risk was also reduced but this did not reach statistical significance. Only four of the 14 cohort studies were included in the meta-analysis and, again, CRC risk was lower in IBS patients but this was not statistically significant.

Abstract

OBJECTIVES

Colorectal cancer (CRC) is the third most common malignancy in the US. Several factors are associated with increased/decreased CRC risk and often linked to adenomatous colorectal polyps (CRP). Recent studies suggest a lower risk of neoplastic lesions among irritable bowel syndrome (IBS) patients. We aimed to systematically assess the occurrence of CRC and CRP in IBS patients.

METHODS

Searches of the Medline, Cochrane, and EMBASE databases were performed, blindly and independently, by two investigators. Studies of CRC or CRP incidence in IBS patients (diagnosed by Rome or other symptom-based criteria) were eligible for inclusion. CRC and CRP effect estimates were pooled in meta-analyses using random models.

RESULTS

Of 4941 non-duplicate studies, 14 were included, comprising 654,764 IBS patients and 2,277,195 controls in 8 cohort studies, and 26,641 IBS patients and 87,803 controls in 6 cross-sectional studies. Pooled analysis revealed a significantly decreased prevalence of CRP in IBS subjects vs. controls, with a pooled odds ratio (OR) of 0.29 (95% CI (0.15, 0.54)). There was significant heterogeneity between studies (I = 96%, p < 0.01). This finding persisted when studies which did not report pre-cancerous polyps separately were excluded (OR 0.23, 95% CI (0.15, 0.35), I = 85%, p < 0.01). CRC prevalence was lower in IBS subjects, but this did not reach statistical significance (OR 0.40, 95% CI (0.09, 1.77]).

CONCLUSION

Our analyses reveal a decreased incidence of colorectal polyps in IBS, although CRC did not reach significance. Mechanistic studies with detailed genotypic analysis and clinical phenotyping are needed to better elucidate the potentially protective effect of IBS on CRC development.

Address: Department of Clinical Therapeutics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.; Medically Associated Science and Technology (MAST) Program, Cedars-Sinai, 770 N. San Vicente Blvd, Suite G271, West Hollywood, CA, USA.; Karsh Division of Gastroenterology and Hepatology, Department of Medicine, Cedars-Sinai, Los Angeles, CA, USA.; Medical School, University of Cyprus, Nicosia, Cyprus.; University of Texas Health Science Center at Houston, Houston, TX, USA.; Medically Associated Science and Technology (MAST) Program, Cedars-Sinai, 770 N. San Vicente Blvd, Suite G271, West Hollywood, CA, USA. [email protected].; Karsh Division of Gastroenterology and Hepatology, Department of Medicine, Cedars-Sinai, Los Angeles, CA, USA. [email protected].

DOI: 10.1007/s10620-023-07885-6