Associations between neutrophil percentage-to-albumin ratio with all-cause and cause-specific mortality among US cancer survivors: evidence from NHANES 2005-2018.

Background: The neutrophil percentage-to-albumin ratio (NPAR) had been suggested as a potential prognostic biomarker in various health outcomes. However, its association with mortality in cancer survivors remains unclear. Methods: A total of 3,022 cancer survivors from the National Health and Nutrition Examination Survey (NHANES) 2005-2018 were linked to mortality outcomes from the National Death Index (NDI). Weighted Cox proportional hazards models was conducted to investigate the association between NPAR and all-cause, cancer and cardiovascular disease (CVD) mortality and the hazard ratio (HR) with 95% confidence interval (CI) were calculated. Restricted cubic spline (RCS) was used to clarify the non-linear association. Additionally, analyses for stratification and sensitivity were performed. Results: During a median follow-up of 75 months, 790 all-cause deaths occurred, including 244 from cancer and 209 from CVD. After adjustment for covariates, higher NPAR was independently associated with increased risk of all-cause mortality (HR = 1.09, 95% CI = 1.06-1.13), cancer mortality (HR = 1.05, 95% CI = 0.99-1.12), and CVD mortality (HR = 1.13, 95% CI = 1.06-1.21). The RCS revealed a U-shaped relationship for all-cause and cancer mortality, with thresholds of 12.76 and 13.60, respectively. Below the threshold, higher NPAR was associated with a reduced risk of mortality (HR = 0.90, 95% CI = 0.82-0.99; HR = 0.87, 95% CI = 0.76-0.99), whereas above the threshold, the risk of mortality increased significantly (HR = 1.14, 95% CI = 1.09-1.18; HR = 1.15, 95% CI = 1.07-1.24). Subgroup and sensitivity analyses confirmed these findings. Conclusion: The U-shaped association with all-cause and cancer mortality, along with the linear association with CVD mortality, underscores the potential of NPAR as a valuable prognostic marker in cancer survivors.