Variation in the Incidence and Magnitude of Tumor-Infiltrating Lymphocytes in Breast Cancer Subtypes

The presence of tumor-infiltrating lymphocytes (TILs) is a favorable prognostic factor in breast cancer, and TILs may synergize with chemotherapy and immune checkpoint inhibitor therapy for improved clinical response. A more detailed understanding of the variation in lymphocytic infiltration in breast cancer may aid in identifying subtypes more amenable to immunomodulation.

To determine the median percentage of patients with breast cancer with no, intermediate, or high levels of TIL and assess variations in lymphocytic cell subsets across breast cancer subtypes. EVIDENCE REVIEW: Eligible studies (PubMed, 1990-2015) analyzed tumor lymphocytic, CD8+, and FOXP3+ cellular infiltrates, and used multivariable analyses and quantitative methods for enumerating cell populations. Selection of of studies was performed in accordance with PRISMA guidelines and evaluated by 2 independent appraisers.