Prognostic Value of Systemic Immune-Inflammation Index in Brain Metastases SRS

Overview

This study evaluated the prognostic significance of the systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI) for overall survival (OS) and local tumor control (LC) in patients undergoing primary stereotactic radiosurgery (SRS) for brain metastases. Findings suggest that higher SII and SIRI values are associated with poorer OS, providing objective blood-based biomarkers to complement existing prognostic tools.

Background

Brain metastases are the most common brain tumors in adults, with local control primarily achieved through surgical resection or radiation therapies such as stereotactic radiosurgery (SRS). Prognostic assessment is critical for treatment planning, but current systems like the diagnosis-specific graded prognostic assessment (DS-GPA) rely on subjective clinical measures and lack objective laboratory markers. The systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI), derived from routine blood counts, have shown prognostic value in various cancers but have been underexplored in brain metastases treated with SRS. This study aimed to fill that gap by assessing SII and SIRI as predictors of survival and tumor control after primary SRS.

Data Highlights

The study included patients treated with fractionated SRS between April 2018 and December 2022, excluding those without adequate pre-SRS blood counts or prior brain radiation. SII and SIRI were calculated from neutrophil, monocyte, platelet, and lymphocyte counts obtained before SRS. Outcomes measured were overall survival (OS) and local tumor control (LC) duration, with tumor progression defined by ≥20% volume increase per RANO-BM criteria. Statistical analyses included Cox regression and multivariable modeling to identify associations between SII, SIRI, and clinical outcomes.

Key Findings

• Higher pre-treatment SII and SIRI values were significantly associated with worse overall survival following primary SRS for brain metastases.
• SII and SIRI provided objective prognostic information beyond traditional clinical factors included in DS-GPA.
• Neither SII nor SIRI showed strong predictive value for local tumor control duration, likely due to limited progression events.
• Blood samples were collected prior to systemic cancer treatment and without active infection or inflammation, ensuring indices reflected tumor-related immune status.
• Multivariable Cox regression models confirmed the independent prognostic value of SII and SIRI after adjusting for confounders.

Clinical Implications

Incorporating SII and SIRI into prognostic assessment may enhance risk stratification for patients undergoing SRS for brain metastases by providing objective, blood-based biomarkers of systemic inflammation and immune status. These indices could complement existing tools like DS-GPA, potentially guiding personalized treatment decisions and follow-up strategies. Routine pre-SRS blood counts can be leveraged without additional testing burden.

Conclusion

SII and SIRI are promising prognostic biomarkers for overall survival in patients receiving primary stereotactic radiosurgery for brain metastases. Their integration into clinical practice may improve prognostic accuracy and aid in personalized management.

References

1. References 1-21 as cited in source article