Circulating CD3+CD8+ cell levels were lower in breast cancer patients, elevated posttreatment, and subsequently declining upon recurrence. Elevated plasma chemokine (C-C motif) ligand 2 (CCL2) levels distinguished patients with breast cancer from healthy controls. In summary, circulating CD3+CD8+ CTL and plasma CCL2 levels emerged as promising dual-purpose biomarkers and therapeutic targets in breast cancer management.
Background: Identifying breast cancer markers with superior sensitivity, cost‐effectiveness, and practicality is imperative. Circulating immune cells and plasma cytokines hold promise as potential breast cancer markers.
Aims: To search and validate subtype of circulating immune cells and plasma cytokines as biomarkers for breast cancer patients.
Materials & methods: Using flow cytometry, we investigated circulating immune cell profiles in patients with breast cancer and healthy controls. To validate clinical observations, an orthotopic breast cancer model was established.
Results: We analyzed 19 healthy controls and 27 patients (22 testing group and 5 validation group) with breast cancer and revealed distinct populations, including CD3+CD4+ T lymphocytes, cytotoxic T lymphocytes (CTLs; CD3+CD8+), polymorphonuclear myeloid‐derived suppressor cells (PMN‐MDSCs), and monocytic (M)‐myeloid‐derived suppressive cells. Patients with breast cancer exhibited reduced CD3+CD4+ T lymphocyte, CD3+CD8+ CTL, and CD33+CD15− M‐MDSC levels compared with healthy controls. Diminished CD3+CD8+ CTL levels correlated with advanced cancer grade, extensive intraductal components, and positive lymphatic tumor emboli. Treatment effects included decreased T lymphocyte/PMN‐MDSC levels, contrasting with elevated circulating CD3+CD8+ cell levels posttreatment, subsequently declining upon recurrence in the validation group. Elevated plasma chemokine (C–C motif) ligand 2 (CCL2) levels distinguished patients with breast cancer from healthy controls. Our orthotopic model supported decreased circulating CD3+CD8+ CTL levels in cancer‐bearing mice, followed by a postresection increase.
Discussion: We found that circulating CD3+CD8+ CTL levels decreased in patients with breast cancer, increased after treatment, and decreased again upon recurrence.
Conclusion: Circulating CD3+CD8+ CTL emerged as promising prognostic biomarkers and therapeutic targets in breast cancer management.
Keywords: CCL2; biomarker; breast cancer; circulating immune cells; cytotoxic T lymphocytes.
© 2025 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.