Studies On The Mutations And Expression Of K-ras Gene For Diagnosis Of Pancreatic Cancer

Objective:To investigate the effect of detection mutation and expression of K-ras gene in paraffin-embedded tissue for diagnosis of pancreatic cancer.Methods:K-ras gene 12 codon mutation was detected by mutant allele-specific amplification(PCR-MASA) and K-ras protein expression was detected by immunohistochemistry method in 31 pancreatic cancer cases and 22 non-pancreatic cancer cases. To analyze the diagnostic efficiency of K-ras gene mutation and protein expression, its association with pathological characteristics and the correlation in pancreatic cancer.Results: 1. In 31 pancreatic cancer cases the K-ras gene 12 codon mutation rate was 80.6 %(25/31) and the positive rate of K-ras protein expression was 87.1 %(27/31). In 22 cases without pancreatic cancer the K-ras gene 12 codon mutation rate was 27.3 %(6/22), and the positive rate of K-ras protein expression was 31.8 %(7/22). The K-ras gene mutation rate and the positive rate of K-ras protein expression of pancreatic cancer cases were obviously higher than the cases without pancreatic cancer(P<0.05).2. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of detection K-ras gene mutation for diagnosis of pancreatic cancer were 80.6%(25/31), 72.7%(16/22), 80.6%(25/31), 72.7%(16/22), 77.4%(41/53), respectively. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of detection K-ras protein expression for diagnosis of pancreatic cancer were 87.1%(27/31), 68.2%(15/22), 79.4%(27/34), 78.9%(15/19), 79.2%(42/53). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of combined detection mutation and expression of K-ras gene for diagnosis of pancreatic cancer were 77.4%(24/31), 90.9%(20/22), 92.3%(24/26), 74.1%(20/27), 83.0%(44/53).3. K-ras gene mutation and K-ras protein expression was not associated with pathological characteristics of pancreatic cancer(gender, age, tumor location, tumor size, TNM staging and degree of differentiation).4. K-ras gene mutation and K-ras protein expression was positively correlated(r=0.542,P<0.05).Conclusion:1. The K-ras gene mutation rate and the positive rate of K-ras protein expression of pancreatic cancer cases were obviously higher than the cases without pancreatic cancer. 2. The combined diagnostic efficiency of K-ras gene mutation and protein expression was higher. 3. K-ras gene mutation and K-ras protein expression was not associated with pathological characteristics of pancreatic cancer. 4. K-ras gene mutation and K-ras protein expression was positively correlated. 5. K-ras gene mutation and K-ras protein expression are contribute to the diagnosis of pancreatic cancer.