Abstract
BACKGROUND: Owing to the rarity of metastatic tumors in the small bowel, their clinicopathological features, and prognostic factors remain poorly understood. This study aimed to clarify the clinicopathological features and factors associated with the prognosis of patients with small bowel metastasis from other organs in Japan. METHODS: We retrospectively examined 253 patients who were histopathologically diagnosed with small bowel metastases between January 2008 and December 2017 at multiple institutions in Japan. We identified the clinicopathological features of the condition and determined the factors associated with the prognosis of these patients. RESULTS: Obstructive symptoms were the most frequent clinical presentations (39% abdominal pain and 18% vomiting), while gastrointestinal bleeding was observed in 27% of patients. The diagnostic modalities included enteroscopy (33%), balloon-assisted enteroscopy (30%), and capsule endoscopy (13%). The most common primary tumor was lung cancer (38%), followed by colorectal cancer (18%), gastric cancer (9%), and malignant melanoma (6%). Surgical intervention, including tumor resection or bypass surgery, was performed in 79% of patients. The cumulative survival rates of patients at 12, 24, and 60 months were 49%, 36%, and 22%, respectively. Multivariate analysis identified surgery as a significant factor for improving overall survival (HR = 0.56, 95% CI 0.35-0.89, p = 0.01). CONCLUSIONS: The lung cancer is the most frequent primary tumor of metastatic tumors in the small bowel. Surgical intervention was associated with improved survival outcomes.