Pancreatic cyst fluid DNA analysis in evaluating pancreatic cysts: a report of the PANDA study.

Background: The role of pancreatic cyst fluid DNA analysis in evaluating pancreatic cysts remains unclear.
Objective: Our purpose was to evaluate the utility of a detailed DNA analysis of pancreatic cyst fluid to diagnose mucinous and malignant cysts.
Design: Prospective, multicenter study.
Patients: Patients with pancreatic cysts presenting for EUS evaluation.
Intervention: EUS-guided pancreatic cyst aspirates cytology evaluation, carcinoembryonic antigen (CEA) level determination, and a detailed DNA analysis; incorporating DNA quantification, k-ras mutation and multiple allelic loss analysis, mutational amplitude, and sequence determination.
Main Outcome Measurements: Cyst fluid analysis compared with surgical pathologic or malignant cytologic examination.
Results: The study cohort consisted of 113 patients with 40 malignant, 48 premalignant, and 25 benign cysts. Cyst fluid k-ras mutation was helpful in the diagnosis of mucinous cysts (odds ratio 20.9, specificity 96%), whereas receiver-operator characteristic curve analysis indicated optimal cutoff points for allelic loss amplitude (area under the curve [AUC] 0.79; optimal value > 65%) and CEA (AUC 0.74; optimal value >148 ng/mL). Components of DNA analysis detecting malignant cysts included allelic loss amplitude over 82% (AUC 0.9) and high DNA amount (optical density ratio >10, AUC 0.79). The criteria of a high amplitude k-ras mutation followed by allelic loss showed maximum specificity (96%) for malignancy. All malignant cysts with negative cytologic evaluation (10/40) could be diagnosed as malignant by using DNA analysis.
Limitations: Limited follow-up, selection bias.
Conclusions: Elevated amounts of pancreatic cyst fluid DNA, high-amplitude mutations, and specific mutation acquisition sequences are indicators of malignancy. The presence of a k-ras mutation is also indicative of a mucinous cyst. DNA analysis should be considered when cyst cytologic examination is negative for malignancy.