Role of Neutrophil to Lymphocyte Ratio or Platelet to Lymphocyte Ratio in Prediction of Bone Metastasis of Prostate Cancer

Background: Accumulating evidence has revealed that inflammation might play an important role in the genesis and development of cancer. High levels of neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ration (PLR) are parameters of systemic inflammation which have been identified to be associated with poor prognosis in PCa. Bone is one of the most common sites of metastasis from prostate cancer; however, there are few studies concerning the correlation of NLR, PLR, and bone metastases in PCa. The aim of this study was to evaluate the performance of neutrophil to lymphocyte ratio (NLR) or platelet to lymphocyte (PLR) in diagnosis of bone metastasis of prostate cancer (PCa). Methods: Data of 74 PCa patients without metastases, 51 PCa patients with bone metastases, and 43 patients with benign prostatic hypertrophy (BPH) were retrospectively reviewed. The difference of patients' clinical and laboratory characteristics of the three groups was comparatively studied. ROC analysis was used to evaluate the benefit of adding NLR or PLR to prostate specific antigen (PSA) in prediction of bone metastases. Depending on this cutoff value, patients were divided into high-NLR or low-NLR group, high-PLR or low-PLR group. Results: There were significant differences in NLR and PLR between groups with bone metastases and without bone metastases (p = 0.044; p = 0.030), while there was no significant difference between NLR and PLR of the patients with localized prostate cancer and BPH (p = 0.462; p = 0.102). NLR and PLR were correlated with PSA level in the patients with prostate cancer (p = 0.006, r = 0.247; p = 0.025, r = 0.200). The distribution of PSA showed significant differences between the high-NLR and low-NLR group, as well as between the high-PLR and low-PLR group. By applying the ROC curve method, the AUC values of PSA with NLR or PLR were 0.725 and 0.838 (0.763 -0.913), respectively. Although PSA + PLR had the largest area, there was no statistical significance between PSA + PLR and PSA (p = 0.6992). Conclusions: NLR and PLR significantly increase in PCa patients with bone metastases and are valuable in the diagnosis of bone metastases in PCa patients.