Frequency and prognostic utility of MSI and TILs in advanced noncolorectal GI malignancies.

313Background: Mismatch repair gene mutation status not only has a role in pathogenesis but also has significant clinical implications with respect to treatment with checkpoint inhibitors. Additionally tumor infiltrating lymphocytes (TILs) are also emerging prognostic biomarker and are utilized in adoptive T-cell therapy as well. Methods: This is a retrospective cohort study of patients who were diagnosed with advanced unresectable non-colorectal GI (NCGI) cancers. Biopsy specimens of patients diagnosed between 2009 and 2015 at St. John Hospital and Medical Center were analyzed. Immunohistochemistry panels were performed on a representative tissue sections for microsatellite instability (MSI) testing. TILs were assessed on the hematoxylin and Eosin stained slide of the same tissue section. MSI was interpreted as stable or high and TILs were categorized as ≤5 and > 5 per high power field. Descriptive statistics were generated using frequency distributions, medians and means. Kaplan-Meier analysis was perfo...