The Value Of Detecting K-ras Mutations In Plasma By A Nano Probe System In The Early Diagnosis And Prognosis Of Pancreatic Cancer

ObjectiveAim to establish a method of detecting K-ras mutations in plasma by a nano-fluorescence probe system,and compare the K-ras mutations of patients with pancreatic cancer,patients with benign pancreatic diseases and normal subjects to explore the diagnostic and prognostic value of this method in patients with pancreatic cancer.MethodsThe plasma samples of 68 patients with pancreatic cancer,33 patients with benign pancreatic diseases and 30 healthy donors were collected from January 2014 to July 2015.The diagnoses of all patients were explicit.The DNA was extracted from all plasma samples and was detected for the K-ras gene mutation at codon 12 and 13 by nano-fluorescence probe system.And combined with clinical data,the diagnostic and prognostic value of K-ras gene mutation in pancreatic cancer was analyzed.ResultsOf 68 patients with pancreatic cancer,27 contained K-ras mutation at codon 12,2 contained K-ras mutation at codon 13.And the K-ras mutation rate is 42.6%(29 out of 68).Of 33 patients with benign pancreatic diseases,3 contained K-ras mutation at codon 12.And the K-ras mutation rate is 9.1%(3/33).The difference is statistically significant(P<0.05).30 healthy donors contained wild-type K-ras.K-ras gene mutation showed a sensitivity of 42.6% and specificity of 95.2%,and with a positive predictive value of 90.6% and negative predictive value of 60.6%,and with a youden index of 0.379.The combination of K-ras and CA 19-9 level determination gave a sensitivity for the diagnosis of pancreatic cancer of 85.3%(58/68)of the patients.The K-ras mutation rate in early pancreatic cancer(stage I and II)is 22.9%(8 out of 35),but the mutation rate in advanced pancreatic cancer(stage III and IV)is 60.6%(20 out of 33).The difference is statistically significant(P< 0.05),which is suggested that K-ras mutation in plasma is related to TNM stage.The 6-month survival rate of pancreatic cancer patients with K-ras mutation is 70.3%,and the 6-month survival rate of patients with wild-type K-ras is 86.3%.The difference is not statistically significant(P? 0.05).While,the one-year survival rate of pancreatic cancer patients with K-ras mutation is 28.9%,and the one-year survival rate of patients with wild-type K-ras is 61.8%.The difference is statistically significant(P< 0.05).ConclusionThe nano-fluorescence probe system could certainly detect rare K-ras mutation in plasma.With a low sensitivity and a relatively high specificity,so the diagnostic role of pancreatic cancer is insufficient.And this method is not suitable for early diagnosis of pancreatic cancer.But,the combination with CA 19-9 assay is useful for detection evaluation of pancreatic carcinoma.K-ras mutation in plasma is related to TNM stage and prognosis of pancreatic cancer,and K-ras mutation in plasma DNA may be a predictive biomarker for a poor prognosis of pancreatic cancer patients.