Influence of preoperative chemoradiation on tumor-infiltrating lymphocytes in locally advanced rectal cancer: The STAR-01 cohort.

3611 Background: Preoperative chemoradiotherapy may increase antitumor immunity through enhancing T-cell activation and tumor infiltration. These effects could possibly sensitize tumors to immunotherapies, including checkpoint inhibitors. We explored whether preoperative chemoradiation for locally advanced rectal cancer induces immunologic changes and if the post-operative biological parameters are associated with tumor regression grade (TRG...