Adequacy evaluation and use of pancreatic adenocarcinoma specimens for next‐generation sequencing acquired by endoscopic ultrasound–guided FNA and FNB

BackgroundEndoscopic ultrasound–guided tissue acquisition (EUS‐TA), especially endoscopic ultrasound–guided fine‐needle aspiration (EUS‐FNA), is the mainstay of tissue acquisition for the diagnosis of pancreatic ductal adenocarcinoma (PDAC). Recently, endoscopic ultrasound–guided fine‐needle biopsy (EUS‐FNB) using flexible biopsy needles has been used for patients with PDAC in an effort to increase diagnostic yields and biomarker testing. However, the role of EUS‐TA in biomarker testing for personalized therapy or precise chemotherapy for PDAC is not well established.MethodsPDAC cases with specimens acquired through concurrent EUS‐FNA and EUS‐FNB were identified retrospectively. Smears were prepared from EUS‐FNA sampling, and cell blocks (CBs) were prepared from EUS‐FNB sampling. Rapid onsite evaluation was conducted for all cases for diagnostic adequacy. The adequacy for biomarker testing, including next‐generation sequencing (NGS) and immunohistochemistry (IHC) assays, was evaluated, and cases with smears and CBs adequate for NGS were processed for targeted NGS.ResultsThere were 26 PDAC cases concurrently sampled by EUS‐FNA and EUS‐FNB. EUS‐FNA smears for all 26 cases and EUS‐FNB CBs for 20 cases (77%) were diagnostic for PDAC. Twenty‐one smears (81%) and 11 CBs (42%) were adequate for NGS. Nine cases with both smears and CBs adequate for NGS underwent NGS, which identified clinically significant gene mutation variants, including KRAS, TP53, and SMAD4 mutations.ConclusionsBoth EUS‐FNA and EUS‐FNB can provide optimal material for targeted NGS for PDACs. In PDAC cases subjected to concurrent EUS‐FNA and EUS‐FNB, EUS‐FNA specimens had greater diagnostic yields and more adequate material for NGS than EUS‐FNB specimens, whereas EUS‐FNB was more suitable for IHC‐based biomarker testing.