Relationship of the breast ductal carcinoma in situ immune microenvironment with clinicopathological and genetic features

Abstract

Purpose: The immune microenvironment of breast ductal carcinoma in situ (DCIS) has yet to be fully explored, and the relationship of immune cells to genetic features of DCIS is unknown. Experimental Design: We quantified tumor associated lymphocytes (TIL) and evaluated PD-L1 protein levels by immunohistochemistry in a cohort of pure DCIS (138 and 79 cases, respectively), some of which had copy number (n = 55) and mutation data (n = 20). Results: TILs were identified in the stroma surrounding DCIS (119/138, 86%) and present at a median TIL score of 5% (range, 0%-90%). Most DCIS were negative for tumor cell PD-L1 staining (89%), but 25% of cases were positive for immune cell staining. We obser..