COMPARISON OF DIAGNOSTIC GAINS BY NEXT-GENERATION PROFILING, CONVENTIONAL CYTOLOGY AND HISTOLOGY IN PATIENTS WITH LOCALLY ADVANCED PANCREATIC ADENOCARCINOMA FOLLOWING EUS-GUIDED BIOPSY

Aims Endoscopic ultrasound (EUS)-guided biopsy is the method of choice for obtaining pancreatic tissue for pathological and molecular diagnosis. Next-generation sequencing (NGS) has been applied to EUS-guided biopsies and may select different molecular profiling. Our study aimed to compare side-by-side the diagnostic yield achievable by genetic identification of somatic mutations detected with NSG versus histological and cytological typing in advanced pancreatic carcinoma (LAPC), in samples acquired under EUS-guidance.

Methods This was a prospective observational cohort study conducted at Humanitas Research Hospital, registered on ClinicalTrials.gov (NCT03578939). The study included 33 patients referred for naive locally advanced pancreatic adenocarcinoma, who underwent EUS-guided tissue acquisition using a 22G Franseen needle. Material was obtained for both pathological diagnosis and storage in the biobank for DNA extraction and NSG analysis. Twenty-one genes were selected to be prioritized for computational analysis.

Results The final diagnosis was pancreatic ductal adenocarcinoma (PDAC) in all patients (100%). A macroscopic core was obtained in 30 patients (91%). In 3 lesions no cores adequate for histological analysis were obtained, but cytological analysis revealed tumoral cells from PDAC. Good quality DNA was extracted from 32 out of 33 samples (97%). Most samples (84%) carried at least two clearly pathogenic mutations in different genes. Detection of KRAS mutation allowed for molecular diagnosis of PDAC in 30/32 patients (93.75%).

Conclusions Franseen needles are good for both pathological and molecular diagnosis of PDAC. NGS applied to our sampling reached the best diagnostic gain, overcoming established cytological and pathological readings, if single approaches are considered.