Study of colorectal cancer with Crohn's disease

Crohn's disease (CD) cases have been increasing and prolonged cases are now frequent. In addition, in Japan, more cases with concomitant malignant disease have also recently been reported. There is a particularly high risk of cancer occurring simultaneously in the lower rectum and the anal area.

Two-hundred and eighty-six patients with CD had undergone surgery at this department, up to December, 2005. We studied malignant diseases concomitant with CD, based on empirical examples.

Thirteen (4.5%) were cases concomitant with malignant disease: six patients had colorectal cancer, 1 had rectal carcinoid, 1 had stomach cancer, 1 had uterine cancer, 1 had thyroid cancer, 1 had skin cancer and 2 had acute leukemia. Regarding the seven cases other than colorectal cancer, they were all juvenile patients under the age of 50, except for the stomach cancer case (69 years of age). Among the 6 cases of colorectal cancer, 5 cases were anorectal cancer and 1 was lower rectal cancer. The average age was 42.8 years (30-54 years) and the average term from CD occurrence to cancer diagnosis was 208 months (69-387 months). The one case with lower rectal cancer was intramucosal cancer which did not recur after surgery. The five cases of anorectal cancer were advanced, with invasion of the adjacent organs and 2 of them were unresectable. Four cases were of the infiltrative type, and regarding the histological findings, 4 cases were cancer with mucous production and 1 case was a poorly-differentiated endocrine tumor. Four cases had a history of anal fistula, but there was no clear causal relationship.

In Japan, prolonged CD cases have been increasing and more and more cases of malignant disease with concomitant CD have been reported. There is a particularly high risk of cancer occurring simultaneously in the lower rectum and the anal area. Therefore, careful observation, taking all appropriate diagnostic surveillance modalities into consideration, is thus believed to be important in order to achieve an early detection of such cancer.