LAUSR

64Background: At present, the clinical management of resected GC is only based on risk stratification according to the AJCC staging. This project evaluates molecular factors on formalin-fixed, paraffin-embedded (FFEP) specimens of the primary tumor radically resected in an omogeneous group patients considered at poor prognosis according by nodal involvement (pN3a/b AJCC 7th edition) and included in the ITACA-S trial. Methods: Matched pairs of tumor-normal GC FFPE specimens collected from 15 patients were subjected to whole-exome sequencing using TruSeq Exome technology and NextSeq500 (Illumina). Somatic mutations (single-nucleotide variants) were identified, filtered and then searched for recurrently mutated genes and pathways. Patients with recurrence (cases) were compared to an equally-sized sample of patients without recurrence (controls) with the same follow up time (60 months). Results: Clinical characteristics of 15 pts: median age 61 (41-71) yrs. Nodal involvement: pN3a( 5); pN3b (10). Histotype: I...