Sialyl-tn antigen as a marker of colon cancer risk in ulcerative colitis: Relation to dysplasia and DNA aneuploidy

Background & Aims: Expression of the mucin-associated carbohydrate antigen sialyl-Tn (STn) and DNA aneuploidy has each been shown to correlate with ma lignant transformation in patients with sporadic colon cancer and in those with ulcerative colitis (UC). This study aimed to determine how STn express ion topographically and temporally relates to aneuploidy and neoplasia in p atients with long-standing UC, Methods: Twenty-six patients enrolled in a c ancer surveillance program were studied, and 1691 mucosal specimens from re peated colonoscopies and colectomies were assessed in a standardized, prosp ective fashion for the presence of dysplasia, aneuploidy, and STn antigen. Results: STn was expressed in 47% of specimens from 6 patients who underwen t colectomy for dysplasia and 7% of specimens from 6 well-matched patients who underwent surgery for medical intractability. Seven other patients who never developed dysplasia or aneuploidy expressed STn in 6% of biopsy speci mens. STn expression was independent of aneuploidy in colons both with and without dysplasia, Of 5 patients with aneuploidy but without dysplasia, 4 e xpressed STn earlier than aneuploidy, Conclusions: In UC, STn antigen and D NA aneuploidy are independent markers of neoplastic transformation. Determi nation of STn expression may complement dysplasia and aneuploidy for identi fication of risk for colonic neoplasia in UC.