Prognostic role of the systemic immune-inflammation index and pan-immune inflammation value for outcomes of breast cancer: a systematic review and meta-analysis.

Objective: This review examined the literature for evidence on the prognostic ability of systemic immune-inflammation index (SII) and pan-immune inflammation value (PIV) for predicting overall survival (OS) and disease-free survival (DFS) in breast cancer patients.
Materials and Methods: PubMed, Embase, Scopus, and Web of Science were searched with Google Scholar for gray literature. All types of studies reporting the association between SII or PIV and OS or DFS of breast cancer were eligible.
Results: 13 studies on SII and 4 studies on PIV were included. Meta-analysis showed that a high SII was a significant predictor of OS (HR: 1.97 95% CI: 1.54, 2.52 I2=76%) and DFS (HR: 2.07 95% CI: 1.50, 2.86 I2=79%) in breast cancer patients. These results did not change on sensitivity analysis and were more or less stable on multiple subgroup analyses. Pooled analysis showed that high PIV was also a significant predictor of poor OS (HR: 2.63 95% CI: 1.46, 4.74 I2=71%) and DFS (HR: 1.64 95% CI: 1.23, 2.17 I2=0%) in breast cancer patients.
Conclusions: High SII and PIV can predict poor OS and DFS in breast cancer patients. High heterogeneity and the observational nature of data are important limitations of the review. Further studies are needed specifically on PIV to increase the strength of the evidence.