Prognostic significance of systemic immune-inflammation index in triple-negative breast cancer

Introduction: The prognostic significance of the systemic immune-inflammation index (SII) in breast cancer is unknown. Here, we aimed to explore the connection between pretreatment SII and the survival of patients with triple-negative breast cancer (TNBC). Methods: We enrolled 160 TNBC patients treated in our hospital between May 2000 and June 2012. We employed the Kaplan-Meier curve and log-rank test to assess overall survival (OS), disease-free survival (DFS), and distant metastasis-free survival (DMFS). We identified the prognostic significance of SII using the Cox regression model. Results: The Kaplan-Meier curve revealed the median OS as 44.2 and 82.4 months in high and low SII TNBC patients, respectively (P<0.001). According to univariate and multivariate analyses, increased SII correlated with poor OS (HR =2.91, 95% CI: 2.00–4.23, P<0.001; HR =2.60, 95% CI: 1.74–3.88, P<0.001). The DFS and DMFS of patients with high SII were 18.8 and 23.8 months, respectively, while those of patients with low SII were 29 and 45.2 months, respectively, (P<0.001). Further univariate analyses showed a significant correlation between SII and DFS and DMFS (P<0.01), while results from multivariate analyses suggested that SII is an independent prognostic factor for DFS (P=0.045), but not for DMFS (P=0.078). The area under the receiver operating characteristics curves for SII to differentiate between long and short OS, DFS, and DMFS were 0.69, 0.60, and 0.64, respectively. Conclusion: Our findings may point to SII having an independent prognostic significance in TNBC patients. Prospective in-depth studies, using a larger sample size, are required to further investigate the precise role of SII in TNBC before clinical use.