DPC4 Expression in the Small Intestinal Adenocarcinomas

BACKGROUND Small intestinal adenocarcinomas (SACs) are rare malignancies of the alimentary tract with uncertain carcinogenesis. METHODS We investigated the expression of deleted in pancreatic cancer 4 (DPC4) in 188 cases of surgically resected SACs, using tissue microarray technology. RESULTS Twenty-four of the 188 tumors showed complete loss of Smad4/DPC4 expression in cytoplasm (score, 0; 12.8%). Eighty-four and 31 cases were moderately and strongly positive, respectively (score, 2 and 3; 44.7% and 16.5%, respectively) and 49 cases were focally or weakly stained (score, 1; 29.1%). Immunohistochemistry analysis showed that the expression of Smad4/DPC4 was related to an increased risk of lymphatic invasion but not to other clinicopathological features of the tumors (tumor location, differentiation, growth pattern, T stage, direct invasion, vascular invasion, and nodal metastasis). There was no significant association between Smad4/DPC4 expression and patient survival. CONCLUSIONS The present research is the first study to evaluate Smad4/DPC4 expression in a large sample of SACs with clinicopathologic correlation. Future studies should focus on the immunohistochemical and molecular characteristics of SACs to clarify their tumorigenesis.