Background: Neutrophil to lymphocyte ratio (NLR) has been proven as a vital predictor of progression of cancer and mortality for a variety of cancers. 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: Prostate cancer survivors with a high NLR were older (73.5 years-old), non-Hispanic white (82.5%), low income (poverty income ratio ≤1, 4.1%), overweight or obese (73.0%), current smokers (8.5%) and longer years after diagnosis (8.8 years) compared to counterparts with a low 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 OR =5.63, 95% CI: 1.92-16.47). 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 ≥3compared to non-smokers. Smoking cessation could benefit these patients in prostate cancer management and reduce the risk of progression and mortality.