Prognostic value of the pretreatment systemic inflammation response index in patients with metastatic colorectal cancer treated with immunotherapy
摘要
The use of programmed cell death protein-1 (PD-1)-targeting monoclonal antibodies has yielded promising therapeutic outcomes in patients with metastatic colorectal cancer (mCRC). However, the identification of reliable biomarkers to guide patient selection for immune checkpoint inhibitor (ICI) therapy remains a critical need. The systemic inflammation response index (SIRI), a cost-effective and easily obtained measure of systemic inflammation and immunonutritional status, has been proposed as a potential prognostic indicator for this disease.
MethodsWe retrospectively analysed the data of 180 consecutive mCRC patients treated with ICIs from January 2017 to April 2024. The pretreatment SIRI was measured, and univariable and multivariable Cox regression analyses were performed to assess progression-free survival (PFS) and overall survival (OS). Internal validation of the predictive performance of the SIRI was conducted using bootstrap resampling (B = 2000 repetitions).
ResultsAn elevated pretreatment SIRI (≥ 1.44) was significantly associated with shorter PFS (median: 4.0 vs. 9.3 months; p = 0.002) and OS (median: 10.9 vs. 20.7 months; p < 0.001). Multivariable analysis confirmed that a high pretreatment SIRI was an independent adverse factor for PFS (HR = 2.0; 95% CI 1.38–2.98; p < 0.001) and OS (HR = 2.2; 95% CI 1.47–3.4; p < 0.001). Internal validation analyses yielded an AUC of 0.59 (95% CI 0.50–0.68) for the SIRI in predicting 12-month mortality, with a specificity of 0.77 and sensitivity of 0.44, indicating modest discriminative performance.
ConclusionThe findings of this study suggest that an elevated pretreatment SIRI is associated with poor survival outcomes in mCRC patients receiving ICIs. However, internal validation indicated that, as a standalone predictive marker, the SIRI had limited discriminability in this real-world cohort. Therefore, the SIRI should be interpreted as a preliminary and exploratory prognostic indicator and may be more clinically informative when combined with established molecular biomarkers and other clinicopathological factors.