Cyclooxygenase-2 and Cytosolic Phospholipase A2 Are Overexpressed in Mucinous Pancreatic Cysts.

OBJECTIVES: Expression of prostaglandin biosynthetic pathway enzymes in mucinous pancreatic cysts is unknown. Cyclooxygenase-2 (COX-2) inhibition is a potential cancer chemoprevention strategy for these lesions. We evaluated the expression of COX-2, cytosolic phospholipase A2 (cPLA2), and protein kinase B (AKT) in the epithelium of pancreatic cysts and correlated enzyme expression with aspirin (ASA) use and cyst fluid prostaglandin E2 (PGE2) concentration. METHODS: Pathology of 80 resected pancreatic cysts was reviewed. Expression of COX-2, cPLA2, and AKT was quantified by tissue immunohistochemistry immunoreactivity scores (IRSs). IRS values were compared between cyst types and (in 30 cases) with matched cyst fluid PGE2 concentrations. RESULTS: The mean IRS was higher in the epithelium of mucinous vs nonmucinous cysts for COX-2 (6.1 ± 4.7 vs 3.2 ± 2.8, P = 0.01) and cPLA2 (6.9 ± 3.0 vs 2.9 ± 2.9, P < 0.001). Cyst epithelial COX-2 expression was higher in mucinous cysts with low-grade dysplasia vs those with high-grade dysplasia or invasive carcinoma (IRS 8.0 ± 3.9 vs 1.5 ± 2.9, P < 0.001), whereas the opposite was found for cPLA2 (6.2 ± 3.0 vs 8.6 ± 2.3, P = 0.005). Cyst fluid PGE2 concentrations did not correlate with either the IRS or a history of low- to moderate-dose ASA use. CONCLUSIONS: COX-2 and cPLA2 are overexpressed in the epithelium of mucinous pancreatic cysts. COX-2 and/or cPLA2 inhibition might prevent the emergence or progression of mucinous pancreatic cysts, but higher doses of ASA or nonsteroidal anti-inflammatory drugs may be necessary to substantially inhibit cyst epithelial COX-2 activity.

Radiofrequency ablation for biliary malignancies.

PURPOSE OF REVIEW: Intraductal biliary radiofrequency ablation (RFA) is an emerging therapeutic modality that directly targets malignant biliary strictures during endoscopic retrograde cholangiopancreatography. This article reviews the technology, endoscopic technique, and reported outcomes of endoscopic RFA in the management of malignant biliary strictures. RECENT FINDINGS: Biliary RFA is feasible and has a high technical success rate. Infectious complications and major hemobilia are the main adverse events requiring intervention. It is unclear whether RFA prolongs biliary stent patency or decreases the need for repeated endoscopic interventions. Retrospective studies suggest a possible survival benefit with RFA. SUMMARY: Intraductal biliary RFA is a promising modality for management of malignant biliary obstruction. Prospective randomized studies are required to determine whether RFA truly confers a survival benefit or decreases the number of biliary interventions.