1175 Ileal Carcinoid Tumors Detected During Screening versus Diagnostic Colonoscopy: Comparison of Tumor Characteristics

INTRODUCTION: Small intestinal carcinoid tumors are the most common type of small bowel malignancy observed. Most are indolent and incidentally found in asymptomatic patients undergoing ileal intubation during routine colonoscopy. Our aim was to survey all patients diagnosed with ileal carcinoid and to compare tumor characteristics for those discovered during screening or diagnostic colonoscopy. METHODS: We reviewed all ileal carcinoid tumor cases from 2005-2018. For each case, we recorded patient age, colonoscopy indication at diagnosis, timing of prior colonoscopy (if ever performed), coexistence of adenomatous polyps in the colon, carcinoid tumor size and stage after resection, and disease-free survival. RESULTS: Twenty-nine (29) cases of ileal carcinoid tumor were identified. Mean patient age at diagnosis was 64. In 5 cases, the tumor was initially identified during urgent surgical evaluation of obstructive symptoms and not during colonoscopy. In the remaining 24 cases, tumors were initially detected during colonoscopy with ileal intubation. Of these, 13 were having initial screening or surveillance. The remaining 11 were having diagnostic evaluation of symptoms, abnormal findings on CT imaging, or both. Table 1 compares carcinoid features for cases detected during screening versus diagnostic colonoscopy. A prior colonoscopy was performed within the preceding 10-year period in 11 cases, and of these, only 3 included terminal ileum intubation. Adenomatous colon polyps were found in 11 of 24 patients, with advanced adenomas identified in 3. Tumor size ranged from 0.5 to 3.7 cm (mean 1.8 cm). Lymph nodes were involved in 21 of 24 patients. In the 3 patients without lymph node involvement, tumors were small (0.5, 0.5, 0.6 cm). At diagnosis, only 1 patient had distant metastases and eventually died from tumor complications 42 months later. Another patient died from an unrelated cause at 99 months after diagnosis. Mean survival-to-date for the remaining 22 patients is 57 months with a range of 2-172 months. CONCLUSION: In our series, most patients with ileal carcinoid tumors were initially diagnosed during colonoscopy rather than during urgent surgery. Nearly all carcinoids discovered during colonoscopy were associated with lymph node involvement at the time of diagnosis. Most, however, did not have or develop distant metastases and have enjoyed prolonged survival. No significant differences in carcinoid tumor size or stage were observed between patients having screening versus diagnostic colonoscopy.