Association between oxidative balance score and all-cause and cancer-specific mortality among cancer survivors.

Background: The Oxidative Balance Score (OBS) represents a novel metric for assessing systemic oxidative stress, where elevated scores reflect increased antioxidant exposure. This study aims to explore the association between OBS and all-cause and cancer-specific mortality among cancer survivors. Methods: An observational cohort study was conducted involving 4099 cancer survivors, utilizing data obtained from the National Health and Nutrition Examination Survey (NHANES) covering the years 1999 to 2018. The endpoints were established by cross-referencing data with the National Death Index (NDI). The OBS was developed based on dietary and lifestyle factors. Cox proportional hazards regression models were employed to examine the relationship between OBS and mortality risks. Restricted cubic spline was utilized to evaluate whether OBS exhibited a nonlinear association with the risk of death. Furthermore, Kaplan-Meier survival curves were generated to assess cumulative survival differences across various OBS outcomes. Results: Over an average follow-up of 84.00 months, 1481 (26.29%) participants died, including 484 (8.9%) who died from cancer. In the fully adjusted model, multivariable Cox regression revealed that each unit increase in OBS was linked to a 1.8% decrease in all-cause mortality risk (HR 0.982, 95%CI 0.972-0.991) and a 2.6% decrease in cancer-specific mortality risk (HR 0.974, 95%CI 0.958-0.991). In the context of all-cause mortality, the risk of death was found to be significantly lower in quartiles Q2, Q3 and Q4 when compared to the OBS in quartile Q1. The hazard ratios (HRs) and 95% confidence intervals (CIs) for Q2, Q3 and Q4 were as follows: Q2 (HR 0.833, 95%CI 0.707-0.981), Q3 (HR 0.789, 95%CI 0.650-0.958) and Q4 (HR 0.699, 95%CI 0.579-0.844). Regarding cancer-specific mortality, the HRs and 95%CIs for Q2, Q3 and Q4 in comparison to Q1 were as follows: Q2 (HR 0.663, 95%CI 0.505-0.869), Q3 (HR 0.688, 95%CI 0.488-0.969) and Q4 (HR 0.595, 95%CI 0.435-0.815). Similar associations were noted when the dietary and lifestyle components of the OBS were analyzed separately. Conclusion: The findings indicate that higher levels of OBS are associated with a decrease in all-cause and cancer-specific mortality among cancer survivors. Our findings may contribute to the refinement of lifestyle intervention recommendations for this population.