Abstract
PURPOSE: Evidence regarding the relationship between albumin-to-alkaline phosphatase ratio (AAPR) and overall survival (OS) in extensive-disease small-cell lung cancer (ED-SCLC) patients is limited. This study aimed to investigate whether AAPR was independently related to OS in ED-SCLC patients after adjusting for potential covariates. PATIENTS AND METHODS: This was a retrospective cohort study of 224 patients with ED-SCLC. The target independent and dependent variables were pretreatment AAPR and OS, respectively. Covariates included age; sex; Eastern Cooperative Oncology performance status score; smoking history; existence of metastasis to organs such as the bone, lung, liver, brain, malignant plural effusion and others; sum of organ metastasis (≤3, >3), evaluation of first-line treatment; and sum of treatment lines (<2, ≥2). Student's t test or chi-squared test was used to analyze the associations between AAPR and clinical characteristics. Kaplan-Meier survival analysis and Cox's proportional hazards regression model were used to assess the prognostic value of AAPR for OS. RESULTS: The average patient age was 60.51±8.73 years, and 87.95% were men. A non-linear relationship between AAPR and OS was detected, with an inflection point of 0.35. The hazard ratios (HRs) of the left (AAPR <0.35) and right sides (AAPR ≥0.35) of inflection point were 0.04 (95% CI=0.00-0.70, p=0.0268) and 0.52 (95% CI=0.16-1.64, p=0.2659), respectively. Kaplan-Meier analysis showed a median OS of 9.73 months (95% CI=8.6-12.33) for AAPR <0.35 and 13.7 months (95% CI=11.43-16.37) for AAPR ≥0.35 (log-rank p<0.0001). The Cox proportional hazards model showed that AAPR <0.35 increased the risk of death after adjusting for potential confounders (HR=1.65, 95% CI=1.11-2.46). In subgroup analysis, the trends of HRs were increased across all subgroups with AAPR <0.35 after stratification. CONCLUSION: Pretreatment AAPR might be served as an independent prognostic indicator in ED-SCLC patients. Our findings should be further validated in large-scale and prospective clinical trials.