High Rates of Ki-ras Point Mutation in Both Intra- and Extra-hepatic Cholangiocarcinomas

The presence of the Ki-ras gene mutations in 14 cases of intrahepaticcholangiocarcinoma (IHC) and nine cases of extrahepatic cholangiocarcinoma(EHC) were investigated by polymerase chain reaction-singlestrand conformation polymorphism analysis. To obtain enrichedtumor cell DNA, the microdissection method was used on formalin-fixedparaffin-embedded tissue sections. Point mutations at codon12 of the Ki-ras gene were detected in seven (50%) of the 14cases of IHC and six (67%) of the nine EHC cases. In all butone of the ras gene mutation cases, G to A transitions in thesecond position of codon 12 were detected, the exception beinga G to T transition in the same position in one IHC. No pointmutations were detected at codon 13 or 61 in either IHC or EHC.Furthermore, there was no demonstrable correlation between Ki-rasmutation and patient age, tumor Stage, histological findingsor prognosis. The present results demonstrated a higherparticipationof Ki-ras gene mutations in EHC than found in previous studies,and provided a confirmation and extension of the results earlierreported by Tada et al, and Tsuda et al, for IHC.