Tumor-associated lymphocytes and macrophages are related to stromal elastosis and vascular invasion in breast cancer

The tumor microenvironment plays a critical role in breast cancer progression. Here, we investigated tumor-infiltrating lymphocytes (TILs) and associations with macrophage numbers, tumor stromal elastosis, vascular invasion, and tumor detection mode. We performed a population-based retrospective study using data from The Norwegian Breast Cancer Screening Program in Vestfold County (2004-2009), including 200 screen-detected and 82 interval cancers. The number of TILs (CD45+, CD3+, CD4+, CD8+, and FOXP3+) and tumor-associated macrophages (CD163+) was counted using immunohistochemistry on tissue microarray slides. Lymphatic and blood vessel invasion (LVI and BVI) were recorded using D2-40 and CD31 staining, and the amount of elastosis (high/low) was determined on regular HE-stained slides. High numbers of all TIL subsets were associated with LVI (p ≤ 0.04 for all), and high counts of several TIL subgroups (CD8+, CD45+, and FOXP3+) were associated with BVI (p ≤ 0.04 for all). Increased levels of all TIL subsets, except CD4+, were associated with estrogen receptor-negative tumors (p