Optimizing Next-Generation Sequencing Analysis of Pancreatic Cancer Using Endoscopic Ultrasound-Guided Fine-Needle Biopsy: A Tertiary Care Experience

Introduction: Endoscopic fine needle biopsy (EUS-FNB) is an effective tissue sampling modality for diagnosing pancreatic cancer. Genomic sequencing is becoming essential with the emerging targeted therapies in pancreatic cancer. However, the feasibility of commercial comprehensive next-generation sequencing on tissue obtained from EUS-FNB is unknown. We aimed to examine the success rate of genomic sequencing utilizing tissue from EUS-FNB and correlate it with procedural characteristics. Methods: We retrospectively reviewed a consecutive cohort of patients who underwent a diagnostic EUS-FNB during the workup of a pancreatic mass, over 5 years, at our institution. Genomic results, patient demographics, tumor characteristics, and technical aspects of the EUS-FNB were reviewed. Needle passes were grouped into 3 categories, namely, 1-2 passes, 3 passes, and 4 or more passes. Tumor location was grouped as distal (involving the body or tail) or proximal (head, neck, or uncinate). Results: A total of 396 patients underwent endoscopic ultrasound with pancreatic mass biopsy as part of the routine diagnostic workup. Tumor sequencing from the pancreatic EUS-FNB was requested from 101 patient samples. The remaining samples had no sequencing performed. Of the 101 patients, sequencing was successful in 88 samples (87%). Tumor purity information was available in 71 samples; the average purity was 32% (range 20-90%). Genomic sequencing was unsuccessful in the remaining 13 samples (13%) due to inadequate tissue. The cancer stage distribution was the following: I (9%), II (10%), III (14%), and IV (67%). The median number of needle passes to obtain sufficient tissue for completion of sequencing was 3 (range, 1-5). When compared to 1-2 needle passes, additional needle passes were not superior in yielding successful tumor sequencing (3 passes OR 1.2, 95% 0.36 – 4.3, P=0.730; 4-5 passes OR 3.70; 0.42 – 32.28, P=0.237). Compared to 22-gauge needles, 25-gauge needles did not yield superior tissue samples (OR 2.20; 95% 0.26 – 18.38; P=0.468). On multivariable logistic regression (Table 1), distal tumor location was more likely to yield successful genomic sampling (OR 6.08; 95% CI 1.16 – 31.96; P=0.033). Conclusion: Comprehensive genomic sequencing of all stages of pancreatic cancer can be achieved using EUS-FNB. Tumor location was associated with higher success of genomic sequencing. Additional FNB needle passes, and needle gauge was not associated with increased yield. Table 1. - Multivariable regression model showing predictors of successful next generation sequencing using EUS-FNB Odds Ratio 95% CI P-value Tumor Axis (cm) 0.712 0.197 – 2.576 .604 Passes 1 to 2 .336 Passes 3 1.114 0.297 – 4.182 .873 Passes 4 to 5 5.294 0.569 – 49.254 .143 Needle gauge 22 Needle gauge 25 2.850 0.313 – 25.957 .353 Tumor location proximal Tumor location distal 6.082 1.157-31.963 .033