Prognostic Value of the Preoperative Platelet-to-leukocyte Ratio for Oncologic Outcomes in Patients Undergoing Radical Cystectomy for Bladder Cancer

Abstract

Background: Currently, stratification of patients with bladder cancer (BC) mainly relies on histopathologic and clinical staging. Furthermore, inflammation plays an important role in the pathogenesis of BC. With the preoperative platelet-to-leukocyte ratio (PLR), we introduce a novel prognostic marker based on routine hematologic values in patients undergoing radical cystectomy (RC).

Patients and methods: In our cohort of 665 patients undergoing RC (2004-2015) for urothelial carcinoma of the bladder (UCB), we analyzed a variety of preoperative hematologic parameters. We investigated the effect of thrombocytosis, leukocytosis, and the PLR on the oncologic outcomes, including cancer-specific survival (CSS), progression-free survival (PFS), and overall survival (OS). Both univariate (log-rank test) and multivariate (Cox regression) analysis were performed. The prevalence of thrombocytosis and leukocytosis and differences in the PLR was assessed using the Mann-Whitney U test. The cutoff levels for leukocytosis, thrombocytosis, and the PLR were defined using receiver operating characteristic curve analysis, with the 5-year CSS as the binary classifier.

Results: A PLR of ≤ 28 (CSS, P = .033; OS, P = .029) and leukocytosis (CSS, P = .01; OS, P = .001; PFS, P = .003) were significantly associated with adverse oncologic outcomes using the log-rank test. On multivariate regression analysis, the PLR (CSS, P = .022; OS, P = .025) remained a significant prognostic marker among the standard staging variables and hemoglobin level. Advanced BC disease was significantly more prevalent in the patient subgroup with a low PLR (pT2-pT4, 35%; vs. pT ≤ 1, 24%; P = .006) and leukocytosis (pT2-pT4, 46%; vs. pT ≤ 1, 30%; P < .001; pN⁺, 49%; vs. pN0, 39%; P < .047).

Conclusion: To the best of our knowledge, the present study is the first report of the preoperative PLR as a prognostic factor in patients undergoing RC for UCB. Compared with other inflammatory markers in BC, the PLR can be assessed without additional effort. External validation and its combination with other parameters might improve current prognostication systems for UCB.

Keywords: Bladder cancer; Inflammation; Leukocytosis; Prognostic markers; Radical cystectomy; Thrombocytosis; Urothelial cell carcinoma.