We have investigated the distribution of chemokine receptor 4 (CXCR4) and CD8-positive, tumour-infiltrating T lymphocytes (CD8+ TILs) in breast cancer subtypes and explored the relationship between them and the well-established conventional prognostic markers, including axillary lymph node involvement.

A total of 250 breast cancer patients were included in the study. The patients were separated into luminal A+B, HER2 enriched/overexpressed (HER2+), and triple-

negative, on the basis of their staining characteristics, via conventional staining methods. Immunohistochemical (IHC) staining for CXCR4 and CD8+ TILs were performed on the archival tissues from each patient.

With increasing intensity of CXCR4 staining, there was a higher incidence of lymph node metastasis (p < 0.01). Similarly, there was a positive correlation between the primary tumour size, HER2+ subtype, lymphovascular invasion, and axillary lymph node involvement. Dense lymphocytic infiltration was observed in HER2+ and triple-negative patients. No correlation between CD8+ TILs in all sites and breast cancer subtypes was discovered. A reverse correlation was discovered with CD8+ TILs stained only intratumorally and CXCR4 expression.

In conclusion, lymph node involvement correlates with higher CXCR4 expression in all breast cancer subtypes. Conversely, no such correlation is found with CD8+ TILs.