Sa1192

EUS Guided Biopsy of Sub-Mucosal Lesions of Gastrointestinal Tract: PRO-Core Is the Needle of ChoiceNam Q. Nguyen, William Tam, Andrew Ruszkiewicz

Endoscopic ultrasound (EUS) guided biopsy allows cytologic and/or histologic diagnosis ofsub-mucosal lesions of the gastrointestinal tract (GIT). The diagnostic yield with fine needleaspiration (FNA), however, is often unsatisfactory (~30-40%). A newly developed Pro-Coreneedle (PCN) is able to obtain core tissue and may improve diagnostic yield. AIM: Tocompare the performance of two EUS guided biopsy needle systems, FNA versus PCN, inthe evaluation of sub-mucosal lesions in the upper GIT. METHODS: Data related to patientsreferred for EUS and possible guided biopsy of sub-mucosal lesions in the upper GIT over24 months were retrospectively reviewed. All specimens were prepared as cell-block forhisto-cytological analysis. Measured outcomes were presence of diagnostic material, abilityto perform immunohistochemistry (IHC), provision of a diagnosis, and complication.RESULTS: Of 84 patients who had EUS evaluation of an upper GIT sub-mucosal lesion, 30patients did not have biopsy (lipoma=14, duplication cysts=6, vascular compression=1 andno abnormality=9). EUS-guided biopsy were performed in 54 patients, using 19-22G FNA(n=34) and 22G PCN (n=20) system, to clarify the tissue diagnosis of a hypo-echoic sub-mucosal mass. There were no differences in age (61.1±2.6 vs. 59.2±5.3 yrs), gender (13M:17Fvs. 3M:8F), site (22gastric : 8duodenal : 4esophageal vs. 17gastric : 1duodenal : 2esophageal)or size (2.1±0.1 vs. 2.1±0.3 cm) of biopsied lesion between the FNA and PCN groups,respectively. Biopsy with PCN obtained significantly more diagnostic material than FNA,leading to a substantially higher diagnostic yield (18/20 vs. 14/34; P ,0.001). Of the 17suspected spindle cell tumours from the PCN group, IHC study (c-kit stain) were successfulin all cases and provided tissue confirmation of 10 leiomyomas and 7 gastrointestinal stromaltumours (GIST). In contrast, only 7/14 patients with FNA needle had sufficient material foradditional IHC study (P=0.008, vs. PCN), confirming GIST in only 3/12 of suspected spindlecell tumours. Neither group had abdominal pain or clinical significant bleeding after thebiopsy. CONCLUSIONS: EUS guided biopsy with 22G PCN has substantially higher histo-cytological yield than that with FNA needles (90% vs. 41%) and without any complication.PCN, therefore, should be the needle of choice for tissue acquisition of sub-mucosal lesionsin the GIT.

Sa1193

Quantitative Endoscopic Ultrasound Elastography (Q-EUS-E) in theDifferential Diagnosis of Solid Pancreatic Masses: A Validation StudyJulio Iglesias-Garcia, Jose Larino-Noia, Enrique Dominguez-Munoz

Background: Quantitative endoscopic ultrasound elastography (Q-EUS-E) is considered asa useful tool for the differential diagnosis of solid pancreatic masses. However there arecertain drawbacks concerning the methodology of performing the elastographic evaluationAim of the study was to validate and determine the accuracy of Q-EUS-E in the differentialdiagnosis of solid pancreatic masses, performed according to a well-established protocol, ina large series of patients. Methods: 199 consecutive patients (mean age 64 years, 17-90years, 121 male), who underwent EUS for the evaluation of solid pancreatic masses wereprospectively included in the study. EUS-elastography was performed under conscioussedation with the linear Pentax EUS (EG-3830-UTK) and the Hitachi-PREIRUS processor.Two different areas (A and B) were selected for quantitative elastographic analysis: Area Ais a representative area of the mass and B refers to a soft peripancreatic reference area. Thequotient B/A (strain ratio) was considered as the result of the elastographic evaluation. Finaldiagnosis was based on surgical histopathology or, in non-operated cases, on imagingassessment; EUS-guided fine needle biopsy and clinical follow-up. Data are shown as medianand 95%CI. Diagnostic accuracy of Q-EUS-E for detecting malignancy was calculated afterdrawing the corresponding ROC curves. Results: Size of solid pancreatic masses was34.88±17.4 mm (mean±SD). Tumors were located in the head of the pancreas in 133patients, in the body in 53 patients and in the tail in 13 patients. Final diagnoses werepancreatic adenocarcinoma (n=135), inflammatory mass (n=38), malignant neuroendocrinetumor (n=11), benign neuroendocrine tumor (n=4), metastasis (n=4), pancreatic lymphoma(n=3), autoimmune pancreatitis (n=2) and mesenchymal lesions (n=2). Q-EUS-E was feasiblein all patients. Strain ratio levels in different pancreatic solid lesions are show in table.The strain ratio was significantly higher among patients with pancreatic malignant tumorscompared with those with benign lesions. ROC curve showed, for a cut-off point of 9.5 (AUC=0.951), a sensitivity, specificity, PPV, NPV and overall accuracy in detecting malignancy of100%, 91%, 97%, 100% and 98%, respectively. Conclusion: Q-EUS-E is a very useful toolfor the differential diagnosis of solid pancreatic masses, performed under a well-establishedprotocol, confirming previous results.

Sa1194

Barriers to Endoscopic Ultrasonography in South and South East AsiaFurqaan Ahmed, Khawar Mehdi

Introduction: Colorectal cancer (CRC) is the fourth leading cause of cancer death worldwide.CRC screening has been shown to reduce the incidence of CRC and is now standard ofcare in the West. Objective: To assess EUS knowledge and usage among gastroenterologistsin South and South East Asia. Methods: Gastroenterologists from South and South East Asiaattending the International Gastroenterology and Hepatology Forum (IGHF) in Yangon,Myanmar in November 2012 were surveyed, using a questionnaire, regarding EUS usagein their countries and their knowledge of the indications for performing an EUS. Results:

S-225 AGA Abstracts

74 gastroenterologists were included in this study. 69% (51) were male. 65% (48) were inacademic practice. The doctors were from the following countries: Pakistan 23 (31%), SriLanka 2 (3%), Myanmar 32 (43%), Philippines 9 (12%), Laos 5 (7%), and Cambodia 2(3%). The doctors have been in practice for a time ranging from 1 to 48 years. EUS isavailable in Pakistan, Philippines, and Sri Lanka and is not available in Myanmar, Cambodiaand Laos. Of the 34 gastroenterologists from countries where EUS was available, only 12(35%) had EUS facilities in the city where they practice. Two doctors performed EUSthemselves. 57 (77%) said EUS was useful for tumor staging. When asked about whichtumors could be staged by EUS, the following were cited: Esophagus 86% (49), Small bowel40% (23), Rectum 65% (37), Lung 18% (10), Spleen 5% (3), Pancreas 54% (31), andkidney 2% (1). When asked about other indications for performing an EUS , the followingwere cited: 1. Abnormalities of the gastrointestinal wall 70% (29), 2. Abnormalities of thekidneys 8% (3), 3. Abnormalities of the biliary tree 43% (17), 4. Abnormalities of the heart8% (3), 5. Pancreatic cysts 55% (22), 6. Kidney cysts 8% (3), 7. Tissue sampling ofgastrointestinal wall lesions 48% (19). There was no difference in knowledge of EUS indica-tions between those gastroenterologists from countries where EUS was available and thosefrom countries lacking EUS.When asked about obstacles to performing EUS in their countries,the following reasons were cited: 1. Cost 50% (37), 2. Doctor awareness 19% (14), 3.Patient awareness 18% (13), 4. Availability 54% (40), 5. Lack of trained doctors 49% (36).Conclusion: Based on this sample of gastroenterologists representing six countries from theregion, there appears to be limited knowledge of the indications for EUS in South and SouthEast Asia. EUS is not available in half of the countries. Issues relating to cost, lack ofawareness, availability, and physician training limit EUS use in this region.

Sa1195

Exposure-Efficacy Relationship (ER) for Adalimumab During Induction Phaseof Treatment of Adult Patients With Moderate to Severe Ulcerative ColitisNael M. Mostafa, Doerthe Eckert, Rajendra S. Pradhan, Sven Mensing, Anne Robinson,William Sandborn, Stephen B. Hanauer, Jean-Frederic Colombel, Roopal Thakkar, WalidM. Awni

Background: The efficacy and pharmacokinetics (PK) of adalimumab administered subcuta-neously to patients with moderate to severe ulcerative colitis (UC) was studied in a Phase3 clinical trial (ULTRA 2). The purpose of this exposure-response analysis was to characterizethe relationship between adalimumab trough concentration (Tconc) and clinical remissionand response per Full Mayo Score (FMS). Methods: Adult patients with moderate to severeUC (N=518) were enrolled, where 260 patients received placebo and 258 received adalimu-mab for the first 8 weeks (160 mg on Wk 0, 80 mg on Wk 2 and 40 mg every other week).Serum adalimumab Tconc was measured immediately prior to dosing at Wk 0, 2, 4 and 8and efficacy (remission/response) was assessed at Week 8 based on FMS. The relationshipbetween Week 8 remission/response and Tconc was explored by grouping subjects intoTconc quartiles and plotting Tconc vs remission/response rates. Only patients with availableTconc at Week 8 were included in this analysis. The ER was also assessed using logisticregression. Two logistic regression models (linear and Emax models) were fit to the individualER data for remission/response at Week 8. In the Emax model, the maximum of upper95% limit of the observed remission/response was used for Emax. Results: The ranges ofadalimumab Tconc quartiles were ,5, 5-8.7, 8.7-11.7 and .11.7 mcg/mL. The Tconc vsremission quartile plots showed a clear ER at Week 8. Higher adalimumab Tconc wereassociated with higher rates of remission. The quartile plots for response showed that thepercentage of subjects with response at Week 8 was higher for the second and third Tconcquartile compared with the first quartile. The percentage of subjects with clinical responseat Week 8 did not increase with increase in adalimumab Tconc beyond the third quartile.Logistic regression ER models for remission (Figure 1 and Figure 2) showed a statisticallysignificant relationship between the percentage of patients with remission at Week 8 andadalimumab Tconc (p,0.001 and p=0.011 for linear and Emax models, respectively).Goodness-of-fit plots showed that both models describe the data adequately. For response,the logistic regression models also showed a statistically significant relationship (p ,0.001and p=0.0324 for linear and Emax models, respectively), but the ER observed with responsewas flatter compared to remission. Conclusions: A statistically significant ER was identifiedbetween adalimumab Tconc and remission during the induction phase. The ER for responseappeared to be shallower compared to that for remission. This indicates that dosing regimensthat result in higher exposures could provide greater efficacy in some patients.

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