Colorectal carcinoma and preceding fistula in Crohn's disease

An increased risk for intestinal carcinoma is known in Crohn's disease, but there are also several reports on patients with perianal fistula and later carcinoma at this location - so to call fistula associated carcinoma.

We retrospectively investigated 591 patients with CD who underwent abdominal surgery during the last 10 years (1997-2006) and found seven patients (5 male, 2 female, median age: 53 years (range 37-74)) with colorectal cancer (Dukes A-C), four of them (57%) with fistula associated CRC. These seven patients with CRC were matched 1:3 to randomly selected Crohn's patients based on age. The medical records of these 21 patients (11 with perianal fistula (52%)) were evaluated with respect to duration and pattern of intestinal involvement of CD, fistula history, intestinal surgery, perianal surgery, prior immunosuppressive and 5-ASA derivative intake.

Colorectal cancer was significantly (p=0.048) associated with longstanding anorectal fistula (median=11 years (range 0-28 years)) in the CRC group compared to the matched Crohn's patients (median=1 year (range 0-6 years)). Earlier colonic surgery seemed to protect from later malignancy (p=0.036). No significant symptoms preceded rectal carcinoma, except for new blood drainage from fistula in 2 patients. Two patients underwent ileocolonoscopy within 1 year before the diagnosis of malignancy and 2 patients underwent MRI of the pelvic region within 4 months.

Colorectal carcinoma is frequently associated with the presence of longstanding anorectal fistula.