Signification of Systemic Immune-Inflammation Index for prediction of prognosis after resecting in patients with colorectal cancer.

Purpose: Systemic inflammatory response has been reported to be associated with prognosis in cancer patients. The aim of this study is to investigate the association between Systemic Immune-Inflammation Index (SII), a novel inflammation-based prognostic score and long-term outcomes among patients with colorectal cancer (CRC) after resection.

Methods: We retrospectively investigated 733 patients who underwent resection for CRC between January 2010 and December 2014 at the Jikei University Hospital and explored the relationship between SII, calculated by multiplying the peripheral platelet count by neutrophil count and divided by lymphocyte count, and overall survival. In survival analyses, we conducted Cox proportional hazards models, adjusting potential confounders including TNM stage, serum CEA, serum CA 19-9, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and platelet count.

Results: In multivariate analysis, age ≥ 65 years (p = 0.003), tumor location (p = 0.043), advanced TNM stage (p < 0.001), serum CA 19-9 > 37 mU/ml (p < 0.001), and SII (P for trend = 0.017) were independent and significant predictors of poor patient survival. Compared to patients with low SII, those with high and intermediate SII patients had poorer survival (Hazard ratio 2.48; 95% CI 1.31-4.69, Hazard ratio 1.65; 95% CI 0.83-3.27, respectively).

Conclusion: The Systemic Immune-Inflammation Index might be an independent and significant indicator of poor long-term outcomes in patients with CRC after resection.