KI-RAS MUTATIONS AND THE CARCINOEMBRYONIC ANTIGEN LEVEL IN FINE-NEEDLE ASPIRATES OF THE PANCREAS

OBJECTIVE: To evaluate the sensitivity and specificity of the carcinoe mbryonic antigen (CEA) immunoassay and Ki-ras genotyping as adjuncts t o the cytologic diagnosis of pancreatic fine needle aspirates (FNAs). STUDY DESIGN: A retrospective study of 30 patients with pancreatic mas ses evaluated with CEA immunoassay and gel or hybridization analysis o f allele-specific polymerase chain reaction for mutant Ki-ras (codons 12 and 13). DNA was isolated from fixed, paraffin-embedded samples. Di agnoses were correlated with cytologic evaluations and patient outcome . RESULTS: Diagnoses included 17 pancreatic carcinomas, 3 other malign ancies and 10 benign lesions. Sixty-five percent of all FNAs had mutat ed Ki-ras, and 42% of samples with altered Ki-ras had multiple mutatio ns. Replicate FNA samplings in five of six patients had concordant gen otypes. Sensitivities for diagnosis were as follows: cytology alone, 7 6%; CEA alone, 82%; Ki-ras alone, 82%; cytology plus CEA, 100%; cytolo gy plus Ki-ras, 94%. Although specificities for Ki-ras (30%) and CEA ( 50%) individually were low elevated CEA level and mutated Ki-ras in a sample with negative cytology strongly indicated false negative cytolo gy. CONCLUSION: The addition of either or both the CEA assay and Ki-ra s mutation analysis enhances the sensitivity of the cytologic diagnosi s of pancreatic carcinoma by FNA.