Neutrophil-to-lymphocyte ratio is associated with accelerometer-measured physical activity levels in breast cancer survivors.

Introduction: Physical activity (PA) has been associated with remarkable benefits in breast cancer (BC) survivors. However, the physiological mechanisms that underlie these benefits are not well understood and the published results are inconsistent and weak. Some authors suggest that some biomarkers, particularly those related with inflammation, insulin resistance, or sexual hormones may account for some of these benefits. Most studies have used self-reported tools to assess PA.

Objective: To explore the association between objectively assessed PA and potentially related biomarkers.

Methods: A cross-sectional study was performed in a single hospital in Madrid, Spain. Candidates were BC survivors older than 18, who had finished their treatments. PA was assessed through accelerometers. Biomarkers related with insulin resistance (glucose, insulin, IGF-1, IGFBP-3), inflammation (C-reactive protein (CRP), neutrophil-lymphocyte ratio (NLR), interleukin (IL) 1, IL-6, IL-8, IL-10, TNF, sexual hormones (progesterone, testosterone, estrogens, androsterone), hypothalamic-pituitary axis (HPA) (cortisol), autonomic nervous system (ANS) (noradrenaline), and oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG) were assessed.

Results: Data of 91 women (mean age: 51.4 ± 8.1 years, mean BMI (kg/m): 25.9 ± 4.5) were analyzed. Sedentary time (β (SE): - 0.001 (0.001), p-value 0.040) and vigorous PA time (β (SE): 0.010 (0.004), p-value 0.026) were significantly associated with NLR, but not with other biomarkers.

Conclusions: PA was not associated with biomarkers related to insulin resistance, sexual hormones, HPA, ANS, and oxidative stress. Neither was it associated with typical biomarkers of inflammation. An unexpected but consistent direct association with NLR was found. This relationship deserves further confirmation.