Venous thromboembolism risk prediction in ambulatory cancer patients: clinical significance of neutrophil/lymphocyte ratio and platelet/lymphocyte ratio

Abstract

Neutrophil/lymphocyte (NLR) and platelet/lymphocyte (PLR) ratios might represent a yet unrecognized risk factor for venous thromboembolism (VTE) in cancer out-patients receiving chemotherapy. Accordingly, this study was aimed at analyzing the significance of these novel markers in the risk prediction of a first VTE episode in a population representative of a general practice cohort. To this purpose, a mono-institutional cohort study was conducted to retrospectively analyze NLR and PLR in 810 consecutive cancer out-patients with primary or relapsing solid cancer at the start of a new chemotherapy regimen. Over a median follow-up of 9.2 months, VTE occurred in 6.7% of patients. Incidental VTE was diagnosed at time of restaging in 47% of cases. Median pre-chemotherapy NLR (p = 0.015) and PLR (p = 0.040) were significantly higher in patients with intermediate risk class who developed symptomatic VTE with a twofold increased VTE risk for both inflammation-based markers (NLR: p = 0.022; PLR: p = 0.037) and a worst 1-year VTE-free survival for patients with high NLR or PLR. However, only PLR (HR = 2.4, p = 0.027) confirmed to be an independent predictor of future VTE in patients in the intermediate risk class in multivariate analysis, together with ECOG performance status (HR = 3.4, p = 0.0002) and bevacizumab use (HR = 4.7, p = 0.012). We may, thus, conclude that PLR, but to a lesser extent NLR, could represent useful clinical predictors of VTE, especially in selected categories of patients such as those in the intermediate risk class in whom the assessment of PLR could allow a better risk stratification of VTE without additional costs to the national health systems.

Keywords: chemotherapy; inflammation; neutrophils; platelets; venous thromboembolism.