This study examines the prognostic significance of TILs and CD8+ in patients with eBC treated with dds-CT. From a total of 5,320 patients enrolled in seven prospective clinical studies conducted by the HECOG between 1996 and 2022, 3,646 patients were deemed eligible having donated tissue for central assessment and translational analysis. All patients had received adjuvant dds-CT, including taxanes and anthracyclines, as part of relevant protocols. Adjuvant endocrine therapy and radiotherapy were administered as clinically indicated. Tumor samples were assessed for stromal TILs, stromal CD8+ (sCD8+), intratumoral CD8+ (iCD8+), and total CD8+ density using immunohistochemistry on tissue microarray cores. Intrinsic breast cancer subtypes defined by immunohistochemistry (IHC4), a cost-saving surrogate of gene expression analysis, is frequently used to guiding treatment decisions based on the expression of ER (estrogen receptor), PgR (progesterone receptors, HER2, and Ki67. The analysis explores the prognostic value of these immune markers in the overall cohort and across different molecular subtypes.
