Endoscopic Ultrasound Tissue Acquisition for Genomic Analysis of Pancreatic Cancer Using Liquid Next-Generation Sequencing: 21

Introduction: Tumor genotyping may allow for improved prognostication and targeted therapy for pancreatic adenocarcinoma (PDAC). We aimed to compare endoscopic ultrasonography (EUS) with fine needle aspiration (FNA) to fine needle biopsy (FNB) for obtaining sufficient tissue for genomic analysis and theranostic potential. Methods: A retrospective cohort study of patients undergoing EUS-FNA and EUS-FNB with either positive or suspicious cytology for PDAC between March 2016 and December 2017. Demographic, procedural, and cytology data were recorded. Genetic alterations were recorded and Kaplan-Meier survival curves were calculated. Results: The study included 167 patients, 145 patients had FNA and 22 patients underwent FNB. Overall, 117 samples (70.1%) were sufficient for liquid NGS. FNB resulted in a higher proportion of patients with sufficient samples compared to FNA (90.9% vs 66.9%; P = 0.02). In multivariable modeling, FNB (OR 4.90, 95% CI 1.09 - 22.11, P = 0.04) and positive family history (OR 2.98, 95% CI 1.10 - 8.03, P = 0.03) were associated with sufficient sampling for genomic testing. FNB was more likely to obtain sufficient tissue from tumors <= 3cm (100% vs. 68.4%, P = 0.017) and tumors located in the head/neck of the pancreas (100% vs. 63.1%, P = 0.03) compared to FNA. The most commonly identified alterations were in KRAS (88%), TP53 (68%), and SMAD4 (16%). Conclusion: EUS can reliably obtain sufficient tissue from PDAC for targeted liquid NGS for prognostication and theranostics. FNB should be considered when tumor genotyping is requested, especially for tumors <=3 cm or tumors located in the head/neck of the pancreas.21_A Figure 1. Patient Characteristics21_B Figure 2. Sample Sufficiency and Tumor Characteristics21_C Figure 3. Univariate and Multivariable Analysis (a) and Sample Sufficiency by Tumor Size and Location (b)