Combination analysis of genetic alterations and cell proliferation in small intestinal carcinomas

We analyzed K-ras andp53 mutations, microsatellite instability (MSI), and l oss of heterozygosity (LOH) using the polymerase chain reaction (PCR) metho ds, as well as p53 expression and the Ki-67 labeling index (LI) using immun ohistochemistry in 10 duodenal and 10 jejunal/ileal carcinomas. K-ras mutat ions were detected in two duodenal (20%) and three jejunal/ileal (30%) carc inomas and p53 mutations in one (10%) and three (30%), respectively. LOH of 17p was detected in two duodenal (20%) and two jejunal/ileal (20%) carcino mas and p53 expression in four duodenal (40%) and four jejunal/ileal (40%). One duodenal (10%) and two jejunal/ileal (20%) carcinomas demonstrated MSI . LOH of APC was detected in three jejunal/ileal (30%), but none of the duo denal carcinomas. The Ki-67 LI was 44% in duodenal and 52.6% in jejunal/ile al carcinomas. A subset of small intestinal carcinomas showed involvement o f K-ras and p53 mutations, LOH of APC, and MSI. A difference was also appar ent for LOH of APC between duodenal and jejunal/ileal carcinomas.