High frequency of K-ras mutations in biliary duct carcinomas of cases with a long common channel in the papilla of Vater.

The frequency of K-ras mutation in biliary duct carcinomas in different locations and the relationship to the form of the junction of the pancreaticobiliary duct (JPBD) are not understood clearly. These points were investigated in the present study. Thirty-seven biliary duct carcinomas in patients without anomalous JPBD were investigated for K-ras mutations. Regarding location, 12 were hilar, 4 in the upper, 11 in the middle, and 10 in the lower portion of the duct. Furthermore, with 14 cases for which the form of the JPBD could be confirmed by endoscopic retrograde cholangiopancreatography or postoperative cholangiopancreatography, division was made into two types: those with a long common channel (>5 mm) in the papilla of Vater (type 1, n = 4), and the other with a shorter or nonapparent common channel (type 2, n = 10). The overall frequency of K-ras mutation was 30%, the incidence gradually increasing from upper to lower regions. K-ras mutations were significantly more frequent in biliary duct carcinomas associated with long common channels (P < 0.05). These results suggest that a long common channel may bear a relation to K-ras mutations in biliary duct carcinogenesis, presumably through its influence on pancreatic juice regurgitation.