Clinical Characteristics of Crohn's Disease-Associated Cancer with a Focus on Endoscopic Surveillance

Long-term Crohn's disease (CD) increases risk of cancer. However, data on the clinical characteristics and optimal endoscopic surveillance strategies for CD-associated cancers in Japan remain controversial. This study aimed to investigate the clinical characteristics, diagnostic methods, and treatment patterns of CD-associated cancers at our institution and to consider strategies for effective surveillance in Japanese clinical practice.

We retrospectively analyzed 21 patients with 26 CD-associated cancer locations treated at our hospital between August 2001 and March 2024, focusing on their clinical backgrounds, cancer characteristics, and endoscopic surveillance practices.

Anorectal cancer was the most common (61%), and 57% were stage II or higher at the time of diagnosis. There were 12 cases of fistula-associated cancer, with a median disease duration of 18.5 years, and 7 cases of stage II or higher. Targeted endoscopic biopsy established the diagnosis in 77%, often requiring multiple-site biopsies. Remission or mild endoscopic activity was observed in 75% (6/8) of stage 0-I patients, compared with 20% (2/10) of stage II-IV patients, suggesting a trend toward more advanced cancer with higher endoscopic activity (p = 0.03). Compared with non-anorectal cancers, 33% of anorectal cancers required four or more endoscopic biopsies for diagnosis, and this rate was significantly higher than that of non-anorectal cancers (p = 0.028).

Anorectal cancer was the most common CD-associated cancer, and strictures and active inflammation made early diagnosis difficult. Annual surveillance with multiple-site biopsies of anal lesions was essential.