LAUSR

688Background: Currently, there are no blood biomarkers that reflect the composition of immune cells in the tumor microenvironment (TME) of patients with clear cell renal cell carcinoma (ccRCC). High pre-operative neutrophil-to-lymphocyte ratio (NLR) is associated with adverse oncologic outcomes in ccRCC. However, how NLR relates to the immune cell composition in the TME is not well understood. Methods: We performed flow cytometry on tumor and adjacent normal renal tissue from a prospective cohort of patients who underwent surgery from 6/2015-7/2017. Immune cell populations, as a percent of total CD45+, were compared to baseline age, sex, body mass index (BMI), SSIGN score, sarcomatoid differentiation, and AJCC stage (I-IV). NLR was calculated using pre-operative absolute neutrophil-to-lymphocyte counts and further categorized as inflamed if NLR was ≥ 3. Correlations between continuous variables were performed using Spearman’s rank correlation. Comparisons of means were made using the Wilcoxon signed-rank...