Small bowel adenocarcinoma in Crohn's disease: a rare but devastating complication

Background Small bowel adenocarcinoma (SBA) remains a rare entity but occurs at increased frequency in the setting of chronic Crohn's disease (CD). Our aim was to study the presentation, diagnosis and prognosis of SBA in patients undergoing surgery for CD at a single institution. Methods We reviewed the medical records of all patients with CD complicated by adenocarcinoma of the small bowel from 2000 to 2017. Descriptive statistics and Kaplan-Meier overall survival estimates were calculated. Results In total, 22 patients (14 males) with CD (median duration of Crohn's diagnosis 32 years) were diagnosed with SBA and underwent surgical resection (8 isolated small bowel resections, 12 ileocolic resections, and 2 total proctocolectomies). The median patient age at the time of diagnosis was 54 years (range 22-82 years). A total of 17 patients (77%) underwent cross-sectional CT imaging within 3 months of surgery, a cancer diagnosis was suggested in only one patient. In one other patient, SBA was diagnosed preoperatively on endoscopic biopsy of the terminal ileum. The remaining patients were operated on for obstruction (n = 17), abscess or fistulizing disease (n = 2), and sigmoid cancer (n = 1). For these 20 (90%) patients not suspected to have SBA on preoperative assessment, 5 (25%) were diagnosed intraoperatively on frozen section and 15 (75%) were unexpectedly diagnosed postoperatively on final pathology. T staging was characterized by more advanced tumors (T4: 59%, T3: 27%, T2: 9%, and T1: 5%). Nine patients (41%) had nodal involvement and five patients (23%) had hepatic and/or peritoneal carcinomatosis. The 1-, 3-, and 5-year survival estimates for our cohort were 84%, 30%, and 10%, respectively. Median survival was 30.5 months with median follow-up of 23 months (range 6-84 months). Conclusions SBA in the setting of CD is most commonly found incidentally after surgical resection for benign indications. As such, any suspicious finding at the time of surgery in a patient with chronic CD should warrant careful investigation with frozen section and/or resection. Prognosis for CD complicated by SBA remains poor even in the modern era.