k‐ras Point Mutations in the Supernatants of Pancreatic Juice and Bile Are Reliable for Diagnosis of Pancreas and Biliary Tract Carcinomas Complementary to Cytologic Examination

In order to clarify whether DNA analysis for K‐ras mutation can be used to diagnose cancers in supernatants of pancreatic juice and bile, samples from 29 cases of pancreatic, biliary tract, gastric, and neuroendocrine carcinomas, 1 malignant lymphoma case, 2 cases of pancreatic adenoma, 9 cases of chronic pancreatitis and 21 other non‐cancer cases were examined. Polymerase chain reaction (PCR) products for K‐ras gene codons 2 to 97 of exons 1 and 2 were generated with 33/33 (100%) pancreatic juice and 41/41 (100%) bile samples. By the single strand conformation polymorphism (SSCP) method, point mutations were detected in the pancreatic juice or bile supernatants of 13/13 (100%) pancreas cancer cases, 5/14 (35.7%) biliary tract cancer cases, 1/2 (50.0%) pancreatic adenoma cases and 3/9 (33.3%) chronic pancreatitis cases. Direct sequencing confirmed identical point mutations in the supernatants, malignant cells of cytologic smears of pancreatic juice or bile and cancer tissues. The DNA analysis demonstrated the presence of K‐ras point mutations in 3 cases of pancreatic carcinomas with false‐negative cytologic diagnoses. This novel method allows simultaneous testing for genetic abnormalities in supernatants of pancreatic juice and bile, after removing cells for cytologic diagnosis and screening for pancreatic and biliary tract tumors.