Introduction: The incidence of small bowel cancer is rising in the U.S. While the association between inflammatory bowel disease (IBD) and colorectal cancer has been demonstrated, recent studies have suggested that IBD, specifically Crohn's disease (CD), may be associated with an increased risk of small bowel cancer (SBC). This association carries an especially poor prognosis, possibly explained by delayed diagnosis prior to the development of devastating complications. Data on the relationship between CD and small bowel cancer is limited.
Methods: We performed an 8-year longitudinal analysis (2009-2016) of demographic, clinical, laboratory, and treatment data from an IBD registry at the University of Pittsburgh Medical Center to investigate the period prevalence of SBC in this referral population. Patients were identified using computer searches of comprehensive pathology and treatment data, with manual confirmation.
Results: A total of 2,259 IBD patients were included (mean age 46, 52.5% women) of whom 848 had ulcerative colitis (UC) and 1,411 had CD. There were no cases of SBC in patients with UC. There were 8 cases (0.57%) of SBC in patients with CD. Five of these patients had adenocarcinoma, 2 had carcinoid tumors, and 1 had lymphoma. Of the 5 patients with small bowel adenocarcinoma, the mean age was 63.8, 3 (60%) were women, 3 (60%) had a history of smoking, and all were Caucasian. The average duration of CD to time of diagnosis of adenocarcinoma was 30 years. While 4 patients (80%) had exposure to immunosuppressive therapy, only 1 patient (20%) had exposure to anti-TNF biologic therapy. Two of the 5 patients (40%) with adenocarcinoma died from this complication during the observation period.
Conclusion: Small bowel adenocarcinoma is a rare, albeit significant, complication of CD. Development of adenocarcinoma may be associated with longstanding disease and low rates of anti-TNF biologic use. In CD patients with longstanding disease and limited therapy, clinical suspicion for this complication is warranted. Future studies incorporating multiple clinical sites are necessary to better define the incidence and clinical characteristics of SBC in this population and to investigate the feasibility of screening patients with higher susceptibilities.