Ki-ras mutations and the carcinoembryonic antigen level in fine needle aspirates of the pancreas.

Abstract

To evaluate the sensitivity and specificity of the carcinoembryonic antigen (CEA) immunoassay and Ki-ras genotyping as adjuncts to the cytologic diagnosis of pancreatic fine needle aspirates (FNAs). A retrospective study of 30 patients with pancreatic masses evaluated with CEA immunoassay and gel or hybridization analysis of allele-specific polymerase chain reaction for mutant Ki-ras (codons 12 and 13). DNA was isolated from fixed, paraffin-embedded samples. Diagnoses were correlated with cytologic evaluations and patient outcome. Diagnoses included 17 pancreatic carcinomas, 3 other malignancies and 10 benign lesions. Sixty-five percent of all FNAs had mutated Ki-ras, and 42% of samples with altered Ki-ras had multiple mutations. Replicate FNA samplings in five of six patients had concordant genotypes. Sensitivities for diagnosis were as follows: cytology alone, 76%; CEA alone, 82%; Ki-ras alone, 82%; cytology plus CEA, 100%; cytology 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 cytology. The addition of either or both the CEA assay and Ki-ras mutation analysis enhances the sensitivity of the cytologic diagnosis of pancreatic carcinoma by FNA.