Perianal CD & colorectal/anal cancer

Perianal CD & colorectal/anal cancer

December 20, 2022

Issue 24

Clinical Question

Does perianal CD increase risk of colorectal and anal cancer?

Editor’s Bottom Line

Clinicians should be aware that perianal Crohn’s disease is associated with an increased rate of anal cancer, and should perform careful perineal examination in patients with active symptoms


Johansen MP, Wewer MD, Nordholm-Carstensen A, Burisch J. Perianal Crohn’s disease and the development of colorectal and anal cancer: A systematic review and meta-analysis. J Crohns Colitis. Epub ahead of print Sept 20, 2022;


Researchers in Denmark performed this systematic review and meta-analysis of five large cohort studies including 29,548 Crohn’s disease (CD) patients, 26.5% of whom had documented perianal involvement.

During a median six years of follow-up, 127 patients—or 0.43% of the entire study population—developed colorectal cancer. That rate increased to 0.89% among individuals with perianal involvement.

Sixty-eight of the cancers were rectal, while 24 were anal and the most common histological diagnosis was adenocarcinoma, followed by mucinous adenocarcinoma and signet ring cell carcinoma.

Forty-six percent of patients with anal cancer had perianal disease, compared to 37% of those with rectal cancer. Patients with perianal disease were more likely to develop anal than rectal cancer.

A meta-analysis of the five studies confirmed the increased risk of colorectal cancer among those with perianal CD, revealing a pooled odds ratio of 1.66 for developing colorectal cancer, compared to those who did not have perianal involvement (95% Confidence Interval: 1.18–2.34).


Study Design: Systematic review and meta-analysis

Funding: None

Allocation: Not applicable

Setting: Single center

Level of Evidence: 2a