Association between smoking and neutrophil to lymphocyte ratio among prostate cancer survivors: the National Health and Nutrition Examination Survey

BACKGROUND: An elevated neutrophil to lymphocyte ratio (NLR) has been proven as a vital predictor of progression and mortality for prostate cancer. Smoking is a risk factor for increasing NLR. The objective of this study is to examine the effect of smoking on NLR among prostate cancer survivors. METHODS: A total of 354 men adults aged ≥20 years old with prostate cancer were analyzed using the National Health and Nutrition Examination Survey (NHANES) 2005–2016 data. The primary outcome was NLR, which was classified into two levels: high (≥3) and low (<3). Sampling weighted logistic regressions were used for evaluating associations between smoking and NLR among prostate cancer survivors. RESULTS: This study found that 33.2% (n=111) of prostate cancer survivors had an elevated NLR. Prostate cancer survivors with a high NLR were older (mean 73.5 years old), non-Hispanic white (38.5%), higher income (poverty income ratio >1, 34.7%), and longer years after diagnosis (8.8 years) compared to counterparts with a low NLR. Smoking status did not have a significant impact on NLR. The interaction test between race and smoking status was significant (P=0.04). Non-Hispanic black who were current smokers were observed more likely to have high NLR than never smokers [adjusted odds ratio (OR) =3.69, 95% CI: 1.36–9.99]. However, the effect of smoking on NLR was not observed among either non-Hispanic whites or other races. CONCLUSIONS: Non-Hispanic black prostate cancer survivors who were a current smoker were more likely to have NLR ≥3 compared to non-smokers. Smoking cessation could benefit these patients in prostate cancer management and reduce the risk of progression and mortality.