What question did this study set out to answer?

This study aims to identify genetic abnormalities in colorectal cancer associated with ulcerative colitis by analyzing different lesion types in affected patients.

May 29, 2026

Genomic Profiling of Cancerous Areas, Dysplasia, and Background Mucosa in Ulcerative Colitis-associated Colorectal Cancer

Key Points

This study aims to identify genetic abnormalities in colorectal cancer associated with ulcerative colitis by analyzing different lesion types in affected patients.
Examined 12 cases of colitis-associated colorectal cancer using a targeted gene panel analysis.
Analyzed formalin-fixed paraffin-embedded samples from background mucosa, dysplastic lesions, and carcinoma, along with matched blood samples.
Utilized the Todai OncoPanel for detecting mutations in involved lesions.
TP53 mutations found in 12 of 15 carcinoma lesions (80.0%) and 2 of 12 dysplastic lesions (16.7%).
APC and KRAS mutations detected in only one and two patients respectively, indicating differences from sporadic colorectal cancer.
Among analyzed cases, only one patient had both KRAS G12S and CHEK2 K373E pathogenic variants.

Abstract

Background/Aim: Ulcerative colitis (UC) is associated with an increased risk of colorectal cancer (CRC), and unlike sporadic CRC, colitis-associated CRC (CAC) develops through a dysplasia–carcinoma sequence rather than the traditional adenoma–carcinoma pathway. However, studies that have simultaneously analyzed background mucosa, dysplasia, and carcinoma within the same patient remain limited. This study aimed to identify characteristic genetic abnormalities in UC-associated CRC by analyzing background mucosa, dysplasia, and carcinoma using a targeted gene panel. Patients and Methods: Herein, 12 cases of CAC were examined. Formalin-fixed paraffin-embedded samples from eight background mucosae, 12 dysplastic lesions, and 15 carcinoma lesions, together with matched blood samples as normal controls, were subjected to targeted gene panel analysis using the Todai OncoPanel. Results: TP53 mutations were identified in two of the 12 dysplastic lesions (16.7%) and 12 of the 15 carcinoma lesions (80.0%). APC and KRAS, which are frequently mutated in sporadic CRC, were detected in one and two patients, respectively. Among the 12 cases analyzed, dysplasia and carcinoma from the same patient were available for comparison in 11 cases; of these, only one case harbored the pathogenic variants KRAS G12S and CHEK2 K373E, as well as the BRCA2 A1652S variant of uncertain significance. Conclusion: CAC exhibits distinct mutational characteristics compared with sporadic CRC and different genetic abnormalities in each lesion may contribute to the dysplasia–carcinoma sequence.

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