Compartment-specific tumor-infiltrating immune cells and prognosis in breast cancer

Breast cancer immune response is important to patient outcome, but the prognostic interaction between tissue-infiltrating immune cell (TIIC) types is not well-characterized. We evaluated the associations between CD8⁺, FOXP3+, CD20⁺, and CD163⁺ TIICs and breast cancer-specific survival (BCSS). We developed an AI in Halo to score TIIC percentage by compartment (overall, stromal, or intra-tumoral) in 99,051 microarray images from 12,285 female breast cancers. The associations between log-transformed TIIC scores and BCSS were assessed using Cox regression. CD8⁺ and FOXP3+ TIICs were associated with better BCSS in ER-negative disease; CD8⁺ and CD20⁺ TIICs were associated with a better prognosis in ER-positive disease; and CD163⁺ TIICs were associated with a poorer prognosis in ER-positive disease in multi-marker models. These results may have implications for breast cancer immunotherapy.