LOW PREVALENCE OF COLORECTAL NEOPLASIA IN MICROSCOPIC COLITIS: A PROSPECTIVE, MULTICENTER STUDY

Aims Microscopic colitis (MC) is the most frequent condition in subjects undergoing ileocolonoscopy for chronic non bloody diarrhea (CNBD) in Western countries. Emerging evidences have shown a negative association between MC and colorectal cancer. We designed this prospective multicentre study to determine whether the risk of colorectal neoplasia differs significantly between MC and non-MC patients receiving for the first time ever colonoscopy with high-definition and dye-less chromoendoscopy for chronic non bloody diarrhea (CNBD) of unknown origin

Methods Patients with CNBD of unknown origin were prospectively enrolled for ileocolonoscopy with high-definition and digital or optical chromoendoscopy plus multible biopsies in each segment in five referral centres in Northern Italy. The prevalence of colorectal neoplasia (cancer and resected adenoma or serrated lesion) in MC was compared to that observed in a control group negative for MC, inflammatory bowel disease or eosinophilic colitis.

Results From 2014 and 2017, 546 consecutive patients with CNBD were recruited. Among the 492 patients (mean age 53±18 years) fulfilling the inclusion and exclusion criteria, MC was the predominant diagnosis at the histopathological assessment (8.7%). The risk of colorectal neoplasia in MC patients was sharply lower than in non-MC CNBD subjects (odds ratio = 0.39; P ≤ 0.01).

Conclusions This multicenter study confirms MC as a low risk condition for colorectal neoplasia. No surveillance colonoscopy program should be performed for the diagnosis of MC.

The inflammatory pathways reflecting this protective effect against colorectal carcinogenesis should be now investigated.