Lymphocyte-to-monocyte ratio is a valuable marker to predict prostate cancer in patients with prostate specific antigen between 4 and 10 ng/dl

Objective: To evaluate the diagnostic value of serum inflammation markers derived from complete blood count in diagnosis of prostate cancer (PCa). Methods: We retrospectively analyzed the data of 621 patients who underwent prostate biopsy between March 2013 and April 2018. Age, prostate specific antigen (PSA), free PSA, platelet count, neutrophil count, lymphocyte count, monocyte count, prostate volume (PV) and pathology result of the patients were recorded. Patients were grouped as benign prostatic hyperplasia (BPH), prostatitis and PCa. Patients were also grouped according to PSA values, as PSA < 4, PSA 4-10 and PSA > 10 ng/dl. Results: The mean lymphocyte-to-monocyte ratio (LMR) value of the patients with PCa was significantly lower in the entire cohort (p = 0.047). In the PSA 4-10 ng/dl range, LMR value wassignificantly lower in patients with PCa than those with BPH or prostatitis (p = 0.012). In this PSA range, free/total PSA ratio and LMR were significant factors to predict PCa. The cut-off values of LMR, free/total PSA were 3.05 and 0.15 respectively. The sensitivities, spesificities, positive predictive values (PPV) and negative predictive values using LMR cut-off, free/total PSA cut-off and their combination were assessed. Specificity and PPV of the combination group were higher (97.2%, 83.3% respectively) compared to free/total PSA cut-off group (91.6%, 76.6%) and LMR cut-off group (67.8%, 43.7%). Conclusions: LMR is a useful tool at detecting PCa especially in patients with PSA value between 4 and 10 ng/dl. The combination of free/total PSA ratio and LMR improves the diagnostic accuracy more than the use of free/total PSA ratio alone.