Outcomes of patients with small bowel carcinoma treated with appropriate chemotherapy selected on the basis of genetic analysis findings

Small bowel carcinoma is a rare tumor, for which a standardized chemotherapy regimen has not yet been established. Further, this tumor may belong to the group of Lynch syndrome-associated tumors, which are resistant to 5-fluorouracil (5-FU) -based chemotherapy. We investigated mismatch repair protein expression and K-ras gene mutation status in 8 patients with aggressive small bowel carcinoma and determined the chemotherapy regimen used in these patients. Immunohistochemical staining indicated normal mismatch repair protein expression in all surgical specimens. Of 8 patients, 4( 50%) had K-ras codon 12 mutations. Because small bowel carcinoma is not significantly associated with Lynch syndrome, 5-FU-based chemotherapy would be appropriate for the treatment of these patients. The prevalence of K-ras codon 12 mutations was relatively similar to that in patients with sporadic colorectal carcinoma, and the usefulness of anti- epidermal growth factor receptor (EGFR) antibody for the treatment of small bowel carcinoma should be evaluated in the future.