How Colorectal Dysplasia Impacts CRC Risk in IBD

Research led by Jordan E. Axelrad, MD, MPH, co-director of NYU Langone Health’s Inflammatory Bowel Disease Center, and gastroenterologist Adam Faye, MD, director of clinical research at the center, reports long-term outcomes for indefinite, low-grade, and high-grade dysplasia in patients with IBD. Dysplasia, a precancerous condition, is characterized by abnormal cell growth.

Conducted in collaboration with researchers at Karolinska Institutet in Sweden, the study confirms that patients with IBD and colorectal dysplasia face a significantly increased risk of subsequent dysplasia and colorectal cancer (CRC) compared to patients with IBD but without dysplasia. It also clarifies how cancer risk differs by dysplasia grade.

Published in Clinical Gastroenterology and Hepatology, the findings provide some of the most precise CRC risk estimates to date in IBD, which could help refine the guidelines for how often patients with IBD with various levels of risk should undergo colonoscopy surveillance.

“While we have known that dysplasia increases cancer risk in IBD, the exact level of danger for each grade has been unclear,” Dr. Axelrad says. “Our work provides robust, long-term data that can help doctors and patients make more informed decisions about the frequency of cancer surveillance and potential interventions.”

Analyzing Dysplasia Progression Risk

The study analyzed data from the Swedish Patient Register and the ESPRESSO histopathology cohort—two comprehensive, national Swedish health databases—to identify 54,534 patients diagnosed with IBD between 1969 and 2023.

Of those patients, 1,320 had a baseline episode of dysplasia, including 264 with indefinite dysplasia (or unclassified atypia), 1,031 with low-grade dysplasia, and 25 with high-grade dysplasia. The majority of patients (66.9 percent) had ulcerative colitis.

The team then calculated the risk of progressing to high-grade dysplasia or CRC for each baseline dysplasia type. The analysis accounted for other known risk factors, including a patient’s sex, age, IBD classification, and other related medical conditions, which helped isolate the risk posed by different grades of dysplasia alone.

Over a median follow-up of 13.3 years, 5.3 percent of patients with indefinite dysplasia and 8.3 percent of patients with low-grade dysplasia developed either high-grade dysplasia or CRC, compared with just 2.3 percent of patients without dysplasia at baseline.

For patients with high-grade dysplasia at baseline, 40 percent subsequently developed CRC, often within 1 year. Consistent with current guidelines, colectomy may be strongly considered in these patients.

By taking a nationwide approach, the researchers minimized selection bias, while the inclusion of more than 54,000 patients with IBD provided the statistical power to establish some of the most precise CRC risk estimates in the field.

Personalizing Colonoscopy Surveillance

Current guidelines for CRC surveillance in the IBD patient population are based on retrospective data and the inferred risk of dysplasia subtypes, says Dr. Axelrad. “Our analysis of prospectively collected nationwide data provides critical data for refining CRC surveillance guidelines.”

“Our next goal is to see if we can build a personalized risk calculator based on the findings to help clinicians better tailor colonoscopy surveillance plans for each patient, potentially detecting dangerous changes earlier while avoiding unnecessary procedures for those at lower risk,” Dr. Axelrad says.