Procedures were performed on an outpatient basis by a single endoscopist (K.F.B.). EUS was done by using a curved linear array echoendoscope (Olympus Medical, Center Valley Pa). A standardized technique and protocol (Fig. 2A-H,Video 1, available online at www.gie.journal.org) was applied by using a double-channel endoscope (GIF-2TH; Olympus Medical). GSK J4 chemical structure Tumor retraction was preferentially performed by using a 3-pronged anchoring device (OTSC Anchor; Ovesco Endoscopy, Tübingen, Germany) (Figs. 1B, 2A-C, 3). An alternative method to achieve tumor traction consisted of placing an endoloop (HX-400U-30;

Olympus Medical) over a portion of the tumor and retracting this loop with rat-tooth forceps (loop-over-loop method (Figs. 1F, 2F, 4A-D; Video 2, available on line at www.gie.journal.org). The tissue superficial to the tumor was incised by using a standard needle-knife (unroofing, Figs. 1D, 2E). Biopsy samples were obtained from the Erastin ic50 exposed tumor

by using standard biopsy forceps (Fig. 1E) and were submitted for immunohistology and calculation of the mitotic index (mitoses per 50 high-power fields).13 and 14 Surveillance endoscopy and EUS were scheduled at 4 to 6 weeks after the index procedure (Figs. 1H, 2H, 5B). Ligation was repeated if a residual lesion larger than 1 cm was seen. Any thickening of the muscularis propria less than 1 cm was sampled by EUS-guided FNA. If no residual tumor was seen, surveillance endoscopy was scheduled at 1 year. The RLUB technique was attempted in 16 patients (9 male, median age 71 years)

who fulfilled the inclusion criteria (Table 1). Three procedures were aborted MTMR9 because of technical difficulties. Procedure characteristics in 13 patients with successful ligations are outlined in Table 2. Twelve patients with follow-up had confirmed tumor ablation by endoscopy and EUS. Delayed bleeding within 2 weeks of ligation that required hospitalization and blood transfusions occurred in 2 patients; bleeding was successfully treated with repeat loop ligation. One patient reported transient postprocedure pain. Endoloop ligation has been previously reported for small (<2 cm) GISTs11 or large pedunculated submucosal tumors.15 Loop ligation of a GIST with broad attachment to the muscularis propria is technically limited by the tendency for the loop to slip off the tumor as it is closed. If tissue is captured, it is likely to either be superficial to the tumor or contain only part of the tumor. We hypothesized that active retraction of a GIST can evert the tumor-bearing wall and thereby enable full-thickness ligation. This concept is supported by animal studies demonstrating successful full-thickness resection by using a grasp-and-snare technique through a double-channel endoscope.16 Previous experience using a helical screw device to retract and ligate a large, broad-based antral GIST in a patient who subsequently underwent surgery revealed no macroscopic or microscopic evidence of residual GIST.