Long Term Outcomes After EUS-guided Ablation for Cystic Tumors of the Pancreas
Long Term Outcomes After EUS-guided Ablation for Cystic Tumors of the Pancreas
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.
Inclusion Criteria:

 -  uni- or oligo-locular cystic tumors

 -  indeterminate cystic tumors for which EUS-guided fine needle aspiration (FNA) was
 required to obtain additional information

 -  cystic tumors that increased in size during the observation period

 Exclusion Criteria:

 -  cystic tumors which had the typical morphology of serous cystadenomas (i.e., honeycomb
 appearance) and pseudocysts (i.e., parenchymal changes)

 -  evidence of communication between the cystic lesion and the main pancreatic duct
 according to endoscopic retrograde pancreatograms

 -  overt carcinomas with peripancreatic invasion

 -  patients with a bleeding tendency (prothrombin time > 1.5 international normalized
 ratio [INR] or platelet count < 50,000/μL).