The prognostic significance of the lactate dehydrogenase-to-albumin ratio in extensive-stage small cell lung cancer patients receiving chemo-immunotherapy: a multicenter study

BackgroundThe lactate dehydrogenase-to-albumin ratio (LAR) has been acknowledged as an independent prognostic factor for multiple diseases. However, its prognostic significance in extensive-stage small cell lung cancer (ES-SCLC) patients treated with immune checkpoint inhibitors (ICIs) remains ambiguous. This study aims to explore the influence of LAR on the prognosis of ES-SCLC patients undergoing ICIs combined with chemotherapy.MethodsA cohort of 628 patients with ES-SCLC who received ICIs from five hospitals underwent pre-treatment blood biochemical examinations. The overall survival (OS) and progression-free survival (PFS) were analyzed via Cox regression models and Kaplan-Meier survival curves. A multivariate Cox proportional hazards model was constructed to develop a nomogram based on independent prognostic factors. The predictive performance and clinical utility of the nomogram were evaluated using the area under the time-dependent receiver operating characteristic (ROC) curve, calibration curves, and decision curve analysis (DCA).ResultsLAR was identified as an independent prognostic factor influencing PFS and OS. Compared to low levels of LAR, elevated LAR is associated with shorter OS (HR = 4.97,95% CI: 3.32-7.45, P < 0.001) and PFS (HR = 3.02,95% CI: 2.17-4.21, P < 0.001). The ROC curve for OS prediction in the training set exhibited areas under the curve (AUCs) of 0.833 at 1 year and 0.874 at 2 years, whereas the internal validation set showed AUCs of 0.819 for 1- year OS and 0.891 for 2-year OS. The AUCs for 1-year PFS and 2-year PFS in the training set were 0.842 and 0.889, respectively, compared to 0.799 and 0.921 in the internal validation set. Calibration curves verified a good concordance between predicted and observed outcomes in both the training and internal validation sets. In the independent external test cohort, the calibration curve also demonstrated consistency between predicted and observed results. The AUCs for 1-year OS and 2-year OS in the external test set were 0.76 and 0.69. The AUCs for 1-year PFS and 2-year PFS in the external test set were 0.59 and 0.58.ConclusionIn patients with ES-SCLC receiving ICIs combined with chemotherapy, a high pre-treatment LAR was associated with worse clinical outcomes.