Loss of chromosome 18q and DPC4 (Smad4) mutations in appendiceal adenocarcinomas.

Appendiceal adenocarcinomas are uncommon, and the genetic alterations present in these tumors are not well characterized. We studied genetic alterations including loss of chromosome 18q (location of DCC, DPC4, and JV-18 genes), and mutations of the DPC4 (SMAD4) and beta-catenin genes in 28 appendiceal adenocarcinomas, consisting of 17 mucinous and 11 nonmucinous carcinomas. Chromosome 18q loss was present in 57% (12/21) of appendiceal carcinomas including 54% (7/13) of mucinous and 63% (5/8) of nonmucinous carcinomas. Mutation of the DPC4 gene was present in 14% (three of 22) of the carcinomas occurring in one tumor with chromosome 18q loss and in two with unassessed chromosome 18q status. beta-catenin gene mutation was present in 0% (0 of 25) of the carcinomas. Chromosome 18q loss status was not associated with any clinicopathological features. The presence of chromosome 18q loss and DPC4 mutations in appendiceal adenocarcinomas suggests involvement of DPC4 and nearby genes on chromosome 18q (DCC and/or JV-18) in the pathogenesis of appendiceal adenocarcinomas.