Small Bowel Metastatic Tumors: A multicenter Enteroscopy-Based Epidemiologic Study in Taiwan

<title>Abstract</title> <p> <bold>Background</bold> Small bowel tumors are an uncommon cause of gastrointestinal symptoms and obstruction. While primary neoplasms are well-described, metastatic involvement of the small bowel is rare and often underrecognized, posing significant diagnostic challenges. This study aimed to investigate the clinical characteristics, endoscopic findings, and outcomes of metastatic small bowel tumors in Taiwan. <bold>Methods</bold> This multicenter retrospective study reviewed medical records from eight medical centers in Taiwan between November 2007- October 2023. Twenty-eight patients with confirmed metastatic small bowel tumors were analyzed. At the time of diagnosis, patients were categorized into either the isolated small bowel metastasis group (n = 14) or the multi-organ metastasis group (n = 14) to compare clinical variables and survival <bold>Results</bold> The mean age was 60.4 ± 13.3 years with a male predominance (78.6%). Lung cancer was the most common primary malignancy (25.0%), followed by colorectal carcinoma (14.3%), hepatocellular carcinoma (14.3%) and renal cell carcinoma (10.7%). Gastrointestinal bleeding (64%) and small bowel obstruction (18%) were the primary clinical presentations. Computed tomography was nondiagnostic in 35.7% of cases. Enteroscopy revealed ulceration (64%), strictures (46%), and polypoid lesions (36%). Jejunal involvement (71% vs. 29%, p = 0.034) and polypoid lesions (57% vs. 14%, p = 0.046) were significantly more frequent in the multi-organ group. The isolated group showed a trend toward longer survival compared to the multi-organ group (131.2 vs. 65.3 weeks), though this was not statistically significant (p = 0.128). <bold>Conclusion</bold> Metastatic small bowel tumors commonly present with gastrointestinal bleeding. Due to limited diagnostic yield of CT, enteroscopy is essential for accurate diagnosis and should be performed early in patients with history of malignancy and unexplained gastrointestinal symptoms. </p>