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Diagnostic utility of K-ras mutational analysis on bile obtained by endoscopic retrograde cholangiopancreatography
J G Lee1, J W Leung, P B Cotton
1Division of Gastroenterology and Pathology, Duke University Medical Center, Durham, North Carolina, USA.
Background:
Because K-ras oncogene mutations are present in more than 90% of pancreaticobiliary tumors, we tested prospectively whether K-ras mutational analysis of bile samples obtained during ERCP was superior to conventional bile cytology for diagnosis of malignancy.
Methods:
Bile samples from 20 patients undergoing ERCP for evaluation of jaundice were examined by both cytologic study and the polymerase chain reaction for the presence of K-ras oncogene mutations.
Results:
Polymerase chain reaction products were amplified from the bile of 8 of 12 patients with malignancy and 3 of 8 with benign disease; K-ras oncogene mutations were present in 4 of 8 polymerase chain reaction products from malignant samples but absent in all 3 from benign samples. No cytologic results were positive for malignancy.
Conclusions:
Bile obtained during ERCP can yield positive results in K-ras mutational analysis, even when results of conventional bile cytology are negative. In this study, K-ras mutational analysis had a sensitivity of 33% (4 of 12), a specificity of 100%, and a positive predictive value of 100% for diagnosis of malignancy.