Histological inflammation increases the risk of colorectal neoplasia in ulcerative colitis: a systematic review

Background/Aims: Ulcerative colitis (UC) patients are at greater risk for the development of colorectal neoplasia. Several individual studies have demonstrated associations between severity of histologic inflammation and colorectal neoplasia. However, a comprehensive systematic review has not been completed. We performed a systematic review and meta-analysis to explore the relationship between histologic inflammation and risk for neoplasia among available observational studies. Methods: Three databases (EMBASE, MEDLINE and the Cochrane Library) were systematically searched. Studies were included if they included UC patients who underwent colonoscopic assessment and when histologic inflammation and colorectal neoplasia were both reported. Colorectal neoplasia rates were compared. Quantitative meta-analysis was attempted. Results: Four of 1,422 records found were eligible. Results from 2 case-control studies reported a 3.5-fold increased risk for colorectal neoplasia associated with a single point increase in histologic inflammation. This result was further corroborated by one cohort study that demonstrated increased hazard ratios. The second cohort study reported outcomes for patients with normal gross endoscopy, but had increased histological inflammation when neoplasia was assessed. Finally, this study reported increased risk for neoplastic progression by histological inflammation among patients who were normal by gross endoscopic evaluation. Quantitative meta-analysis was unsuccessful due to heterogeneity between study measures. Conclusions: There is strong evidence that histologic inflammation among patients with UC increases the risk of colorectal neoplasia. The depth and nature of assessment of additional clinical variables was varied and may have resulted in greater outcome discrepancy. Additional study related to mechanisms of inflammation-related neoplasia and therapeutic modification is needed.