Unlocking the predictive value of post-neoadjuvant immune biomarkers in breast cancer: neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII)

Abstract Purpose To evaluate the potential prognostic value of two peripheral immune biomarkers—neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII)—in breast cancer patients treated with neoadjuvant chemotherapy, and to assess their association with pathological complete response (pCR) and other predictive factors. In addition, to determine whether prognostic or predictive differences exist between baseline and post-neoadjuvant values of these biomarkers. Methods We analyzed 801 women with early breast cancer treated with neoadjuvant chemotherapy, evaluating clinical and pathological data, survival outcomes, NLR (continuous and categorical) and SII. Results Baseline NLR was significantly higher in younger patients, in those with positive pathological nodes, and in the HER2 + /HR − subtype, while baseline SII was elevated in the triple-negative subtype. Post-neoadjuvant chemotherapy (post-NCT) NLR and SII showed only weak associations with estrogen receptor expression, yet both were independently associated with pCR (post-NCT NLR: OR = 0.91; 95% CI: 0.84–0.98; p = 0.02; post-NCT SII: OR = 0.65; 95% CI: 0.47–0.89; p = 0.008). Neither biomarker showed a significant impact on overall or progression-free survival. Conclusion Post-treatment NLR and SII may reflect chemotherapy-induced immune changes and are associated with pathological complete response, but their additional predictive value is uncertain, and no prognostic impact was observed.