This study compared the predictive value of neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) for pathological complete response (pCR) and disease-free survival (DFS).<h4>Patients and methods</h4>A total of 224 female patients with HER2-positive invasive breast cancer who received NAC followed by surgery at two medical centers (2015-2023) were retrospectively analyzed. The gene discussed is ERBB2; the disease is invasive breast carcinoma.