Validation of the neutrophil-to-lymphocyte ratio as a prognostic factor in a cohort of European prostate cancer patients

Recent studies have expanded the concept that the systemic inflammatory response has an important role in the progression of several solid tumors. The neutrophil-to-lymphocyte ratio (NLR), an easily determinable marker of systemic inflammation, has been associated with clinical outcome in various cancer entities. In the present study, we validated the prognostic relevance of an elevated NLR in a cohort of European prostate cancer patients. Data from 415 consecutive prostate cancer patients treated with 3D conformal radiotherapy at a single tertiary academic center from 1999 to 2007 were included in this retrospective study. Clinical progression-free survival (PFS), distant metastases-free survival (DMFS), and overall survival (OS) were assessed using the Kaplan-Meier method. To evaluate the prognostic relevance, univariate and multivariate Cox regression models were performed for each end point. Based on previously published studies, an NLR a parts per thousand yen 5 was selected as cutoff value for external validation. Multivariate analysis identified an increased NLR as an independent prognostic factor for clinical PFS [hazard ratio (HR) 3.09, 95 % CI 1.64-5.82, p < 0.001], DMFS (HR 3.51, 95 % CI 1.80-6.85, p < 0.001), and OS (HR 2.16, 95 % CI 1.17-3.99, p = 0.013). The NLR seems to represent an independent prognostic marker and should be considered for future individual risk assessment in patients with prostate cancer.