Systemic Immune-Inflammation Index Is Superior to Neutrophil to Lymphocyte Ratio in Prognostic Assessment of Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

Abstract

Background and Methods. As a parameter integrating neutrophil (N), lymphocyte (L), and platelet (P) levels, altered systemic immune-inflammation index (SII) has been investigated in a number of malignant tumor types. Here, we explore the impact of SII in a cohort of 249 breast cancer patients receiving neoadjuvant chemotherapy (NAC), investigating the prognostic value of SII, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR). All patients had complete follow-up data and pathological confirmation of breast cancer by a core needle biopsy prior to NAC treatment and surgery. All blood samples were obtained within one week prior to NAC. Receiver operating characteristic (ROC) analysis was used to determine the optimal cut-off value for patient classification by SII, NLR, and PLR. Associations between clinicopathological variables by SII, NLR, and PLR were determined by a chi-squared test or Fisher’s exact test. Overall survival (OS) analysis was performed using Kaplan-Meier plots, log-rank tests, and Cox proportional hazards regression models. The $Z$ test is used to compare the prognostic ability of SII, NLR, and PLR. Results. SII, NLR, and PLR did not define patient groups with distinct clinicopathological characteristics. SII, NLR, and PLR cut-off values were 547, 2.13, and 88.23, as determined by ROC analysis; the corresponding areas under the curve (AUCs) were 0.625, 0.555, and 0.571, respectively. Cox regression models identified SII as independently associated with OS. Patients with low SII had prolonged OS (65 vs. 41 months, $P=0.017$ , HR: 3.24, 95% CI: 1.23-8.55). In the $Z$ test, the difference in AUC between SII and NLR was statistically significant ( $Z=2.721$ , 95% CI: 0.0194-0.119, $P=0.0065$ ). Conclusion. Our study suggests that the pretreatment SII value is significantly correlated with OS in breast cancer patients undergoing NAC and that the prognostic utility of SII is superior to that of NLR and PLR.