Utility of Mesalazine in Familial Adenomatous Polyposis: Clinical Report of Reduction of Polyp Size in Patients with Ulcerative Colitis, and Safety Examination in Familial Adenomatous Polyposis Patients

: Mesalazine is the gold standard drug for treatment of ulcerative colitis (UC). Here, we describe 4 cases of familial adenomatous polyposis (FAP) patients with UC that showed reduction of intestinal polyp diameter by mesalazine treatment. Of note, the effects of mesalazine on the development of intestinal polyps in FAP patients have not been reported, and we further investigated whether the short-term use of high-dose mesalazine (4 g/day) has harmful effects on FAP patients or not. The authors found that the treatment showed slightly adverse events in FAP patients. However, mesalazine tended to reduce the number of colon polyps in male subjects with FAP. This report provides basic information for planning a double-blind, randomized, clinical trial that aims to show mesalazine's potential to suppress intestinal polyp development in FAP.