A systematic review and meta-analysis investigating the association between constipation and colorectal cancer

Introduction: Colorectal cancer (CRC) ranks as the third most prevalent diagnosed tumor worldwide. While the association between constipation and certain tumors has been established, our study aims to examine the relationship between constipation and colorectal tumors. Materials and Methods: This study employed a systematic review and meta-analysis following the PRISMA reporting guidelines. Searches were conducted without time restrictions until November 4, 2023, across various databases, including PubMed, Scopus, Web of Science, Cochrane, and the Google Scholar search engine. Data analysis was performed using STATA 14, and statistical significance was indicated by P<0.05. Results: This meta-analysis included 18 studies (9 cohort studies and 9 case-control studies) with a total sample size of 1,462,496 individuals. Overall, no significant association was found between constipation and colorectal tumors (OR: 1.09, 95% CI : 0.91-1.31), colon tumor (OR: 1.09, 95% CI : 0.89-1.34), and rectal tumor (OR: 0.95, 95% CI : 0.69-1.32). Subgroup analysis, however, revealed no statistically significant association between constipation and colorectal tumors (OR: 0.93, 95% CI : 0.76-1.14), colon tumors (OR: 0.92, 95% CI : 0.75-1.13), and rectal tumor (OR: 0.92, 95% CI : 0.65-1.21) in cohort studies. In case-control studies, constipation was associated with an increased risk of colorectal tumors (OR: 1.78, 95% CI : 1.12-2.83) and colon tumors (OR: 2.32, 95% CI : 1.58-3.42), while the association between constipation and rectal tumor in case- control studies was (OR: 1.40 (95% CI: 0.62, 2.89). Conclusion: In case-control studies, constipation emerged as a risk factor for colorectal and colon tumors, raising concerns given the high prevalence of constipation globally.