Long Term Outcomes After EUS-guided Ablation for Cystic Tumors of the Pancreas

Overview

Cystic lesions of the pancreas are defined as round, fluid-filled structures within the pancreas detected by radiologic imaging. With widespread use of cross-sectional imaging modalities for various indications, such lesions are now detected in nearly 20% of abdominal imagings, with the majority discovered incidentally. These lesions encompass a wide spectrum of histopathologic entities and biologic behavior, ranging from benign to malignant. Substantial morphologic overlap restricts the accuracy in diagnosing specific type of cystic lesion in spite of recent advances in diagnostic modalities. It is a challenging issue to differentiate each cystic lesion and make a management plan since cystic lesions that are relatively common and asymptomatic may possess malignant potential. Although inflammatory pseudocysts were thought to account for 80-90% of cystic lesions of the pancreas, with cystic tumors accounting for the remaining,10 the latter may occur much more frequently than traditionally estimated. To date, surgical resection is generally recommended for malignant and potentially malignant lesions. However, surgical resection of the pancreas still carries substantial morbidity and sometimes mortality, especially for the cystic lesion located in the head portion. Therefore, management should be individualized by risk-benefit analysis for each patient. Recently, a pilot study of EUS-guided ethanol lavage for cystic tumors of the pancreas reported that complete resolution was achieved in only one-third of patients even though epithelial lining ablation was demonstrated in all resected specimens. Therefore, more effective treatment modalities or ablation agents are required to improve treatment responses. Intratumoral or intraperitoneal injection of chemotherapeutic agent has been used for endobronchial lesions of lung cancer, brain tumors and advanced ovarian cancer.13-16 EUS-guided injection of antitumor material has been reported in advanced pancreatic cancer. Although local injection of chemotherapeutic agents into pancreatic cystic tumors has not yet been reported, it is reasonable to suggest that such an approach may have an additive effect on ablation of the epithelial lining of cystic tumor when combined with ethanol lavage. Paclitaxel, a widely used chemotherapeutic agent, inhibits cell processes that are dependent on microtubule turnover. Due to its highly hydrophobic nature,19 paclitaxel is expected to exert its effect longer when instilled within a closed cavity such as a cyst. The hydrophobic and viscous nature of paclitaxel may reduce the possibility of it leaking through a puncture site and causing complications. The present study evaluated safety, feasibility and response following EUS-guided ethanol lavage with paclitaxel injection (EUS-EP) for treating cystic tumors of the pancreas.