Impact of the systemic immune-inflammation index for the prediction of prognosis and modification of the risk model in patients with metastatic renal cell carcinoma treated with first-line tyrosine kinase inhibitors

Abstract

Introduction: International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) criteria are the most representative risk model for patients with metastatic renal cell carcinoma (mRCC). However, the intermediate-risk group of IMDC criteria is thought to include patients with different prognoses because many of the patients are classified into the intermediate-risk group. In this study, we investigated the impact of systemic immune-inflammation index (SII), which is calculated based on neutrophil count, platelet count, and lymphocyte count, on predicting the prognosis in patients with mRCC, and its usefulness for re-classification of patients with a more sophisticated risk model.

Methods: From January 2008 to January 2018, 179 mRCC patients with a pretreatment and SII were retrospectively investigated. All patients were classified into either a high-SII group or a low-SII group based on the cutoff value of a SII at 730, as reported in previous studies; the overall survival (OS) rates in each group were compared.

Results: The median age was 65 years old. Males and females comprised 145 and 34 cases, respectively. The categories of favorable-, intermediate-, and poor-risk groups in the IMDC model were assessed in 39, 102, and 38 cases, respectively. The median observation period was 24 months. The low-SII and high-SII groups consisted of 73 and 106 cases, respectively. The 50% OS in the high-SII group was 21.4 months, which was significantly worse than that in the low-SII group (49.7 months; p<0.0001). Multivariate analysis showed that a high SII was an independent predictive factor for a worse OS. Next, we constructed a modified IMDC risk model that included the SII instead of a neutrophil count and a platelet count. By using this modified IMDC model, all cases were re-classified into four groups of 33, 52, 81, and 13 cases with 50% OS of 88.8, 45.9, 29.4, and 4.8 months, respectively.

Conclusions: The SII is useful for establishing a more sophisticated prognostic model that can stratify mRCC patients into four groups with different prognoses.

Fig. 1

Correlation between systemic immune inflammation index (SII) and other inflammatory parameters, including (A) C-reactive protein (CRP); (B) platelet count; (C) neutrophil count; and (D) neutrophil-to-lymphocyte ratio (NLR).

Fig. 2

Overall survival (OS) (A) for all cases and (B) OS stratified based on pretreated systemic immune inflammation index (SII).

Fig. 3

Overall survival (OS) stratified based on (A) International Metastatic Renal Cell Carcinoma Database consortium (IMDC) risk model and (B) modified version of IMDC risk model consisting of five factors including systemic immune inflammation index (SII).