Risk of Colorectal Cancer in Patients With Acute Diverticulitis: A Systematic Review and Meta-analysis of Observational Studies

BACKGROUND & AIMS: We performed a systematic review and meta-analysis to assess the prevalence of colorectal cancer in patients with acute diverticulitis. METHODS: We searched MEDLINE from inception through November 2nd, 2017 for studies reporting the prevalence of colorectal cancer in patients with diverticulitis, identified based on the protocol CRD42017083272. This systematic review was conducted in accordance to the MOOSE guidelines. Pooled prevalence values were obtained by random effects models and robustness was tested by leave-one out sensitivity analyses. Heterogeneity was assessed using the Q-test and quantified based on 12 value. The critical appraisal of included studies was performed using the Newcastle-Ottawa scale. RESULTS: Our final analysis included 31 studies, comprising 50,445 patients. The pooled prevalence of colorectal cancer was 1.9% (95% CI, 1.5%-2.3%). Patients with complicated diverticulitis had a significantly higher risk for colorectal cancer (prevalence, 7.9%; 95% CI, 3.9%-15.3%) than patients with uncomplicated diverticulitis (prevalence, 1.3%; 95% CI, 0.1%-2%), corresponding to a pooled prevalence ratio of 6.7 (95% CI, 2.5-18.3). Subgroup analyses did not find significant difference in prevalence when separately pooling studies according to ranking on the Newcastle-Ottawa scale, geographical location or length of follow-up. Meta-regression did not find any association between age and colorectal cancer. Among patients who underwent endoscopy, the pooled prevalence of polyps was 22.7% (95% CI, 19.6%-26.0%), of advanced adenomas was 4.4% (95% CI, 3.4%-5.8%), of adenomas was 14.2% (95% CI, 11.7%-17.1%), and of hyperplastic polyps was 9.2% (95% CI, 7.6%-11.2%). CONCLUSION: In a meta-analysis of observational studies of patients with acute diverticulitis, we found the pooled prevalence of colorectal cancer to be 1.9%. The risk of colorectal cancer was significantly higher in patients with complicated diverticulitis than in patients with uncomplicated diverticulitis.