Evaluation of the Neutrophil-Based Inflammatory Indexes SIRI and NHR in Patients with Extensive-Stage Small Cell Lung Cancer Receiving First-Line Immune Checkpoint Inhibitors Plus Chemotherapy.

To determine the predictive value of two neutrophil-based inflammatory indexes - the systemic inflammatory response index (SIRI) and the neutrophil-to-high density lipoprotein ratio (NHR) - in extensive-stage small cell lung cancer (ES-SCLC) patients treated with first-line immune checkpoint inhibitors (ICIs) and chemotherapy. From May 2020 to May 2023, we enrolled 101 ES-SCLC patients receiving first-line ICIs and chemotherapy in this study. Clinicopathological features, haematological indicators including the SIRI and NHR, treatment efficacy, and patient outcome data were analyzed. There was no statistically significant difference in efficacy or outcome among enrolled patients receiving programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 (PD-L1) inhibitors. The baseline SIRI (P=0.136) and NHR (P=0.453) did not perform well in predicting treatment response. The serum SIRI before treatment was not significantly different from that after two treatment cycles (P=0.113). After two treatment cycles, the serum NHR exhibited a significant decrease from its pretreatment value (P=0.004). The dynamics of the serum SIRI and NHR before therapy and at disease progression did not significantly differ (all P>0.05). The median progression-free survival (mPFS) and median overall survival (mOS) of patients were significantly longer in the high-SIRI group than in the low-SIRI group (mPFS: 7.033 vs. 5.900 months, P=0.020; mOS: 16.233 vs. 11.200 months, P=0.012). Moreover, patients in the low-NHR subgroup presented significantly longer mPFS and mOS than did those in the high-NHR subgroup (mPFS: 7.033 vs. 4.900 months, P=0.002; mOS: 13.933 vs. 8.500 months, P=0.006). Finally, multivariate analyses revealed that Eastern Cooperative Oncology Group performance status, the pretreatment serum SIRI, and the pretreatment serum NHR (all P<0.050) can serve as valuable independent predictors for PFS and OS in patients with ES-SCLC. The baseline serum SIRI and NHR can serve as promising indicators of prognosis, but not treatment response, in ES-SCLC patients receiving first-line ICIs and chemotherapy.