DIAGNOSTIC UTILITY OF K-RAS MUTATIONS IN FINE-NEEDLE ASPIRATES OF PANCREATIC MASSES

Background & Aims: Mutations at codon 12 of the K-ras gene are present in 65%-100% of carcinomas of human exocrine pancreas and could be use d as a potential tumor marker at the tissue level. The purpose of this study was to assess, in a large series of patients, the utility of K- ras mutation analysis to evaluate fine-needle aspirates of pancreatic masses. Methods: One hundred fifteen fine-needle aspirates obtained fr om 93 patients were evaluated retrospectively. Cytological analysis wa s based on the review of cell blocks. Mutations were detected by using artificial restriction fragment length polymorphisms using the HphI a nd BstNI approaches. Results: The sensitivity and specificity of cell block cytology was 64% and 100%, respectively, for the diagnosis of pa ncreatic carcinoma. K-ras mutations were detected in 41 pancreatic car cinomas (sensitivity, 59%) and in one mucinous cystic tumor; specifici ty of ras analysis alone was 100%. The sensitivity and specificity of cytology combined with K-ras mutations were 77.6% and 100%, respective ly. Conclusions: The detection of K-ras mutations would have suggested the diagnosis of pancreatic cancer in 14 cases otherwise not detected by cytology alone. K-ras mutation analysis should be restricted to ce ll blocks containing suspicious, normal-appearing duct cells, or insuf ficient material in the cytological examination.