Genes Detection In Endoscopic Ultrasound-guided Fine-needle Aspiration Biopsy (EUS-FNAB) For Pancreatic Cancer Diagnosis

Pancreatic cancer is a significant health problem worldwide. In recent years, the incidence rate showed an increasing trend. There are about200,000new cases each year. Surgical resection is the only potentially curative treatment. In the absenceof effective methods for early diagnosis, most patients have advanced disease at the time of diagnosis. The degree of the malignancy is high and the prognosis is poor. Pancreatic cancer remains one of the most deadly tumor types. Nearly one halfof the patients have metastasis and35%of the patients presente with advanced lesions of the local tumor when the diagnosis was defined. The resection rate of only15%, the5-year survival rate after diagnosis is less than5%. Therefore, early detection and diagnosis is important to treat the pancreatic cancer and for improving theprognosis. Endoscopic ultrasound-guided fine needle aspiration-biopsy (EUS-FNAB)is a safe and effective technique in diagnosis of pancreatic cancer. It can yields material appropriate for cytological and histologicalexamination. However, diagnostic accuracy by this method is always affected by the location and size of the lesion, the technical skill of the endoscopist, the quantity of tissue obtained, and the qualityof the histology (further impacted by heterogeneity of the tumor). Therefore, a molecular analysis of the specimen obtained by EUS-FNAB has been introduced to improve diagnosis of pancreatic cancer.KRAS mutations are found in75%-95%of resected pancreatic cancer tissues and are thought to be an early event in pancreatic carcinogenesis. Many studies haveattempted to explore the possibility of detecting the KRAS gene mutation to supple ment histo/cytopathologic evaluation of pancreatic masses. In the current study, wedescribe a novel method to detect KRAS gene mutations using peptide nucleic acid-directed polymerase chain reaction (PNA-PCR). We also used TaqMan assays to quantify miRNA levels in FNA samp1es of pancreatic cancer and benign pancreaticmasses to investigate their diagnostic value.In the pancreatic cancer group, KRAS gene mutations were found in48of54cases (88.9%;95%CI:80.5%-97.2%) by the PNA-PCR clamping method. In particular, the combination of KRAS and serum CA19-9(81%) were significantly higher than for serum CA19-9alone (52.4%). In the quantitative detection test, K-ras mutation was detected at high levels (mutant K-ras genes occupied>0.445of all K-ras genes) in patients with pancreatic cancer. Also, There were significant differences inthe expressin of miRNA-210,miRNA-21,miRNA-181a,miRNA-181b,miRNA-196a between pancreatic cancer and benign pancreatic masses(P<0.05).The expression ofmiRNA196a in pancreatic cancer had positive correlation with clinical stage and lymphatic metastasis.In conclusion, our modified PNA-PCR clamping and miRNA detection can effectively detect gene diversification in EUS-FNAB samples. K-ras and miRNA may be important biomarkers for early diagnosis and prognostic assessment of pancreaticcancer. Patients who have a mass in the pancreas with an indeterminate evaluation(due to insufficient material, or determinations of no malignancy or suspicion of malignancy made through histo/cytopathology of EUS-FNAB) would benefit from thegene detection for diagnosis of pancreatic cancer. It may provide a theoretical basisfor esearching the molecular mechanism of pancreatic cancer and be a good attempt of translational medicine.