IPI score as a new prognostic index in extensive stage small cell lung cancer

Personalized prognostic assessment in extensive-stage small cell lung cancer (ES-SCLC) necessitates a comprehensive understanding of systemic inflammatory markers and their impact on survival outcomes. This study aimed to evaluate the prognostic significance of a novel Inflammatory Prognostic Index (IPI) score, derived from four inflammation-related biochemical markers-albumin, C-reactive protein (CRP), neutrophils, and lymphocytes-in patients with ES-SCLC.

Patients diagnosed with ES-SCLC were eligible if adequate clinical, pathological, and follow-up data were available. The IPI score was derived using the formula: C-reactive protein × neutrophil-to-lymphocyte ratio (NLR)/serum albumin. The threshold value for the IPI score was identified using receiver operating characteristic (ROC) curve analysis within the cohort and was applied in an exploratory manner. Based on the predefined cut-off, patients were stratified into low- and high-IPI groups. The log-rank test was used to compare survival times, while Kaplan-Meier curves and Cox regression analyses assessed variables associated with long-term survival. Overall survival (OS) served as the primary endpoint, and progression-free survival (PFS) was evaluated as a secondary endpoint.

Patients with a high IPI score had a mean OS of 9 months (95% CI [4.8-13.2]), while those with a low IPI score had a mean OS of 23 months (95% CI [11.4-34.6]), a statistically significant difference (p = 0.005). The prognostic significance of IPI was confirmed in both univariate (p = 0.003) and multivariate (p = 0.012) analyses.

The IPI score in ES-SCLC patients was associated with prognosis, with a high IPI score indicating poorer OS. These findings should be considered hypothesis-generating and warrant validation in larger prospective cohorts.