Prognostic prediction of systemic immune-inflammation index for patients with gynecological and breast cancers: a meta-analysis

BACKGROUND: Systemic immune-inflammation index (SII) has been suggested to be effective to reflect the inflammatory status and thus may be an underlying biomarker for prognosis prediction. This hypothesis has been demonstrated in meta-analyses on several cancer types. However, there was no study to confirm the prognostic roles of SII for gynecological and breast cancers, which was the goal of our study. METHODS: PubMed, EMBASE, and Cochrane Library databases were searched to collect the articles exploring the associations of SII with prognostic outcomes overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), lymph node metastasis (LNM), and lymphovascular invasion (LVI) in gynecological and breast cancers. The prognostic value of SII was estimated by hazard ratio (HR) or relative risk (RR) with 95% confidence interval (CI). RESULTS: Nine articles involving 2724 patients in 11 datasets were included. Meta-analysis showed that a high SII index was significantly associated with poor OS (HR = 2.12, 95% CI, 1.61-2.79, P < 0.001), DFS/PFS (HR = 2.28, 95% CI 1.52-3.41, P < 0.001) and an increased risk for LNM (RR = 1.34, 95% CI 1.20-1.50, P < 0.001) in patients with gynecological and breast cancers. Subgroup analysis confirmed the prognostic role of SII for OS was applicable to all cancer types, but the association with DFS/PFS and LNM was only significant for ovarian cancer and breast cancer, especially triple-negative breast cancer. No significant association was detected between SII and LVI. CONCLUSION: High SII may be a promising indicator for the prediction of poor prognosis in patients with gynecological and breast cancers, especially ovarian cancer and triple-negative breast cancer.