Current State of and Problems Related to Cancer of the Intestinal Tract Associated with Crohn's Disease in Japan.

Background/aim: Cancer of the intestinal tract (small and large intestine) associated with Crohn's disease has a low incidence but can be fatal if it develops. Thus, the key question is how to deal with this type of cancer. The current study surveyed major medical facilities that treat inflammatory bowel disease (IBD) surgically in Japan in order to examine the clinical features of cancer of the intestinal tract associated with Crohn's disease and explore ways to deal with this cancer in the future.

Patients And Methods: Sixteen major medical facilities that treat IBD surgically were surveyed regarding cancer of the intestinal tract associated with Crohn's disease. The medical facilities had treated 3,454 patients with Crohn's disease, 122 of whom had developed intestinal cancer. The medical facilities were surveyed regarding those 122 patients.

Results: The incidence of intestinal cancer associated with Crohn's disease has increased yearly. Cancer most often developed in the left side of the colon and, particularly, in the rectum and anal canal. Seventy-six percent of cases were diagnosed preoperatively, 4% were diagnosed intraoperatively, while the remaining 20% were diagnosed pathologically after surgery. The most prevalent histological type of cancer was mucinous carcinoma (50%). Forty-two percent of cancers were differentiated, with 4% being poorly differentiated. The surgical procedure performed most often (67%) was abdominoperineal resection. The 5-year survival rate by stage was 88% for Stage I, 68% for Stage II, 71% for Stage IIIa, 25% for Stage IIIb and 0% for Stage IV. Overall, the 5-year survival rate was 52%.

Conclusion: Gastrointestinal (GI) cancer associated with Crohn's disease had an incidence of 3.5%, but also involved a poor prognosis with a 5-year survival rate of 52%. Early detection through surveillance is crucial to improving the prognosis for patients. However, surveillance of the intestinal tract with endoscopy or contrast studies is technically and diagnostically hampered by Crohn's disease and intestinal strictures. A biopsy of the anal canal, a common site of cancer, can readily be performed and constitutes the first step in surveillance.