# Poster Session II - A279 DISTINCT CLINICAL AND PATHOLOGIC CHARACTERISTCIS OF UC-ASSOCIATED NEOPLASIA AMONG PATIENTS UNDERGOING COLECTOMY: A 15-YEAR SINGLE-CENTRE COHORT STUDY

## TL;DR

This study finds that UC-associated neoplasia differs from medically refractory UC in age, disease duration, and pathology, highlighting the need for careful surveillance.

## Contribution

The study provides a detailed 15-year analysis of clinical and pathological differences between UC-associated neoplasia and medically refractory UC.

## Key findings

- Patients with UC-associated neoplasia were older and had longer disease duration compared to those with medically refractory UC.
- Over one-third of patients with dysplasia on biopsy had more advanced pathology at colectomy.
- Most neoplasia cases showed histologically active inflammation and a high rate of PSC.

## Abstract

Despite advancements in endoscopic surveillance approaches and medical therapies, ulcerative colitis (UC)-associated neoplasia remains a major concern in patient care and often necessitates colectomy.

This study aimed to compare the clinical characteristics of patients with UC-associated neoplasia with those of medically refractory UC who underwent colectomy, and to further characterize the pathological features of UC-associated neoplasia.

We retrospectively reviewed medical records of patients with UC who underwent colectomy between January 2010 to July 2024. Patients were categorized as having medically refractory disease (MR) or UC-associated neoplasia as their indication for colectomy. Clinicopathological characteristics were compared between groups, and multivariate logistic regression was performed to identify factors associated with colectomy indications.

A total of 486 patients were eligible for analysis, comprising 356 (73.6%) with MR and 130 (26.7%) with UC-associated neoplasia. Patients in the neoplasia group were older at colectomy (median 47 vs 34 years, p < 0.001) and had a longer disease duration (16 vs 4 years, p < 0.001). In multivariate analysis, concurrent steroid use was ten times more likely in the MR group (Odds ratio [OR] 10.1, 95% confidence interval [CI] 3.9-28.8, p < 0.001), while PSC was ten times more likely in the neoplasia group (OR 0.1, 95% CI 0.05-0.20, p < 0.001). In the neoplasia group, 44.8% had neoplasia in 2 or more colonic segments and 67.7% showed advanced lesions including high-grade dysplasia or adenocarcinoma. When comparing the most advanced findings in preoperative biopsies compared with surgical pathology, 31.9% (37/116) showed discordant findings. Among these, 42.1% (16/38) with low-grade dysplasia and 25.7% (9/35) with high-grade dysplasia on biopsy were found to have more advanced lesions in the colectomy specimens.

Significantly longer disease duration and a high rate of PSC were observed in patents with UC-associated neoplasia. Most neoplasia cases exhibited histologically active inflammation in surgical specimens, and a substantial portion showed multifocal or advanced lesions, Notably, over one-third of patients with dysplasia on biopsy had more advanced pathology at colectomy. These findings underscore the importance of meticulous endoscopic and histologic surveillance in long-standing UC even in presence of active inflammation.

NIH, NIDDK, Hold’em for Life Charity Challenge