Quantitative analysis of T cell subsets in a population of Black women with invasive breast cancer.

We compared T cell subpopulations in primary invasive breast tumors from Black and White women and investigated breast cancer subtype-specific associations of T cell abundance with survival in Black women. Multispectral immune staining was used to quantify helper, cytotoxic, and regulatory T cells in the tumor and stromal compartments of breast tissues. In fully adjusted models, breast tumors from Black women were significantly more likely than those from White women to have a higher abundance of cytotoxic T cells (IRR, 2.41; 95% CI, 1.43-4.05) and helper T cells (IRR, 1.80; 95% CI, 1.06-3.06), and these differences were more pronounced in the tumor than the stromal compartment. Among Black women, higher levels of T cells were associated with improved survival in women with triple-negative breast cancer, whereas a trend of poorer survival was observed in women with HER2-positive tumors. This study contributes to an accumulating body of evidence that the tumor-immune landscape differs between Black and White women.