Impact of neoadjuvant chemotherapy on perioperative immune function in breast cancer patients: a propensity score-matched retrospective study

To evaluate the impact of neoadjuvant chemotherapy on perioperative immune function in breast cancer patients, focusing on CD3⁺, CD4⁺, CD8⁺, and natural killer (NK) cells, as well as the CD4⁺/CD8⁺ ratio. We retrospectively reviewed medical records of breast cancer patients who underwent surgery with or without neoadjuvant chemotherapy at our medical center from January 2020 to December 2022. Patients were matched 1:1 based on propensity scores. Immune cell proportions and the CD4⁺/CD8⁺ ratio were compared on preoperative day one and postoperative days one and seven. Among matched patients, immune cell proportions and the CD4⁺/CD8⁺ ratio did not significantly differ between those who received neoadjuvant chemotherapy and those who did not at any of the three time points. Similar results were observed in chemotherapy-sensitive patients compared to the entire group of patients who did not receive neoadjuvant chemotherapy. However, chemotherapy-insensitive patients had significantly lower proportions of CD4⁺ and NK cells, as well as a lower CD4⁺/CD8⁺ ratio, at all three time points compared to patients who did not receive neoadjuvant chemotherapy. Neoadjuvant chemotherapy may impair immune function in chemotherapy-insensitive patients, but not in those who are sensitive to the treatment.