Fig. 1.

Procedure of nucleic acid sampling during endoscopic ultrasound-guided fine needle aspiration biopsy of pancreatic adenocarcinoma primary tumour and subsequent quantification. a: Schematic representation of the BACAP protocol for RNA and DNA sequencing from EUS-FNAB-W (endoscopic ultrasound-guided fine needle aspiration biopsy wash) materials. The tissue is reserved for anatomopathological diagnostics. Thereafter, the needle is washed (by flushing with air) and kept in RNAprotect Cell Reagent® before pellet isolation and storage at −80 °C until subsequent extraction of both DNA and total RNA and then DNA and RNA sequencing, respectively. In the upper left part: EUS view of a PDAC tumour (white arrows) and the needle within the tumour (dashed white arrow). b: Detail of distribution of EUS-FNAB-W samples and quantification of nucleic acids: for each sample, DNA and total RNA were dissolved in 40 and 20 μL, respectively. Total quantification is given for each sub-group (mean ± SD; median and extremes in parenthesis). Among the 886 samples from the BACAP cohort, nucleic acids (DNA and RNA) were not detectable in 57 samples. From the remaining 829 samples, we selected 426 EUS-FNAB-W samples upon a threshold of both DNA and RNA of at least 0.15 μg per sample. Final analyses were performed on 397 samples as 29 samples were in duplicate. For the 403 remaining samples, either DNA or RNA did not reach a threshold of 0.15 μg.