The lactate dehydrogenase-to-albumin ratio is a prognostic biomarker in extensive-stage small-cell lung cancer

Background: The lactate dehydrogenase-to-albumin ratio (LAR) is a promising prognostic marker in various malignancies. However, its clinical relevance in extensive-disease small-cell lung cancer (ED-SCLC) remains unclear. Methods: We analyzed a total of 221 patients diagnosed with ED-SCLC between January 2008 and December 2021. Patients without treatment response data (n=8), those who did not receive systemic therapy (n=37), and those who lacked baseline LDH values (n=48) were excluded. The LAR was calculated by dividing baseline serum LDH (U/L) by albumin (g/L) and, using ROC analysis, the optimal cut-off level was determined to be 5.71 (sensitivity: 81.5%, specificity: 77.8%). Kaplan–Meier and Cox regression analyses were used to evaluate both progression-free (PFS) and overall survival (OS). Results: A total of 128 patients diagnosed with ED-SCLC were included in our analysis. Patients with an LAR ≥5.71 had significantly shorter median OS (8.1 vs. 20.2 months, p<0.001) and PFS (5.9 vs. 9.4 months, p=0.003) compared to those with an LAR <5.71. In multivariate analysis, a high LAR was an independent predictor of a shorter OS (HR: 3.60; 95% CI: 1.35–9.60; p=0.010) and had a strong association with a shorter PFS (HR: 2.61; 95% CI: 0.95–7.14; p=0.063). Conclusion: The LAR is a simple, cost-effective, and independent prognostic biomarker in patients with ED-SCLC. It could assist in risk stratification and guide treatment decisions in clinical practice.