Objectives: Patients with ulcerative colitis (UC) are at increased risk for developing dysplasia or cancer (neoplasia) and are usually offered colonoscopic surveillance to reduce their risk of cancer-related mortality. The causes of neoplasia may be related to features of UC (the extent, severity, activity, and age at onset of the disease) and to environmental factors (medications, vitamin and mineral supplementation, diet, or industrial pollutants). To determine whether and how the risk (and hence the risk factor profile) for the development of neoplasia changes over time, we conducted an historical cohort study.
Methods: From 445 adult patients with UC proximal to the splenic flexure seen in the Department of Gastroenterology between 1986 and 1992, a random sample of 209 patients was selected. Patients with UC for less than 8 yr or colectomy or neoplasia detected within 2 yr of referral were excluded, leaving 98 patients in the cohort, half of whom had disease onset during or before 1972.
Results: After controlling for age at disease onset and duration of disease at first colonoscopy, we found that patients with an earlier year of disease onset were 85% less likely to develop neoplasia than patients with a later year of disease onset (hazard rate ratio 0.15, 95% confidence interval 0.03-0.66).
Conclusion: These data suggest that the risk for developing neoplasia in UC patients increases with increasing calendar year, implying a worsening risk factor profile.