Clinicopathological Significance of Metastatic Small Intestinal Adenocarcinoma: an Analysis of 67 Cases Published in Japanese

Purpose: Primary small intestinal adenocarcinoma is rare and often diagnosed at an advanced stage, leading to poor prognosis. The aim of this study was to reveal the clinicopathological significance of metastatic small intestinal adenocarcinoma by reviewing the literature and our cases. Materials and methods: We reviewed 67 cases with metastatic small intestinal adenocarcinoma, including our four cases and 63 cases published in Japanese. Results: Among the 67 cases, there were 37 males and 30 females, and the median age was 64 years old. 43 arose in the jejunum and 28 in the ileum. 39 were synchronous and 28 were metachronous, and the most common metastatic site was the peritoneum. Median survival time (MST) of the 67 cases was 18.0 months. Among the 67 cases reviewed, 40 cases underwent chemotherapy, and MST of the chemotherapy group was 22.0 months, whereas that of the best supportive care group was 14.0 months (hazard ratio: 0.65, 95% confidence interval: 0.34-1.22). Conclusions: We reviewed 67 cases with metastatic small intestinal adenocarcinoma, and clinicopathological features were presented. However, this analysis seemed to contain a strong bias. Prospective randomized trials of treatments for small intestinal adenocarcinoma are needed.