Background & AIMS: Long-standing ulcerative colitis has long been recognized as a risk factor for colorectal cancer, but there is still no universal consensus on the optimal management of ulcerative colitis patients with low-grade dysplasia in flat mucosa. Some authorities favor prompt colectomy, whereas others recommend continued surveillance. The purpose of our study was to determine the frequency with which flat low-grade dysplasia in ulcerative colitis progresses to advanced neoplasia (high-grade dysplasia or colorectal cancer) and whether specific variables could predict such progression. Methods: We reviewed the medical histories, colonoscopic findings, and surgical and pathology reports of 46 patients with ulcerative colitis diagnosed with flat low-grade dysplasia on a surveillance colonoscopy. The rates of neoplastic progression, as well as the frequency of advanced neoplasia, were tabulated. We correlated progression with several clinical and colonoscopic variables: the number of biopsy samples positive for flat low-grade dysplasia, the duration and anatomic extent of disease, patient age, and medication use. Results: Among these 46 patients, there were 7 cases of colorectal cancer, 5 of which were stage II or higher. Unexpected advanced neoplasia occurred in 4 of 17 (23.5%) patients who underwent colectomy for flat low-grade dysplasia. On an actuarial basis, the rate of neoplastic progression was 53% at 5 years. No clinical features predicted progression to advanced neoplasia. Cancers, including 2 at advanced stages, developed despite frequent follow-up surveillance examinations. Conclusions: A finding of flat low-grade dysplasia during ulcerative colitis surveillance is a strong predictor of progression to advanced neoplasia. Early colectomy should be recommended for such patients.
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