Endoscopic Ultrasound Fine-Needle Aspiration Cytology Mutation Profiling Using Targeted Next-Generation Sequencing

Objectives: In an era of precision medicine, our aim was to determine the frequency and theranostic potential of mutations identified in malignant lymph nodes (LNs) sampled by endoscopic ultrasound fine-needle aspiration (EUS FNA) of patients with rectal cancer by targeted next-generation sequencing (NGS). Methods: The NGS Ion AmpliSeq Cancer Hotspot Panel v2 (Life Technologies, Carlsbad, CA) and MiSeq (Illumina, San Diego, CA) sequencers were used to sequence and assess for 2,800 or more possible mutations in 50 established cancer-associated genes. Results: Among 102 patients, 89% had 194 pathogenic alterations identified in 19 genes. The identification of KRAS, NRAS , or BRAF mutations suggests that 42% are likely nonresponders to anti–epidermal growth factor receptor therapy. Among KRAS, NRAS , or BRAF wild-type patients, alterations in eight genes linked to alternative therapies were identified in 44%. Conclusions: Our data demonstrate the successful ability to apply a single multiplex test to allow multigene mutation detection from malignant LN cytology specimen DNA collected by EUS FNA.