Retrospective Evaluation and Significance of Neutrophil-to-Lymphocyte Ratio Prior to and 1 month Following Microwave Ablation of Hepatocellular Carcinoma

Abstract

Purpose: Neutrophil-to-lymphocyte ratio (NLR) recently demonstrated predictive value for hepatocellular carcinoma (HCC) recurrence after thermal ablation. Microwave ablation (MWA) has been shown to induce changes in the immune landscape after HCC treatment. This study aims at identifying predictors of local tumor progression (LTP) and post-treatment NLR kinetics after MWA.

Materials and methods: Data from 108 consecutive patients who underwent percutaneous MWA of 119 HCCs with a 2450 Hz/100 W generator in two institutions from October 2014 to September 2021 were retrospectively reviewed. Forty-five HCCs (42 patients) met inclusion criteria for analysis (technique efficacy, pre- and post-treatment NLR availability, follow-up > 6 months, absence of complications). NLR was analyzed prior to therapy and at 1-month follow-up; difference between the two time points was defined as ΔNLR_1stFU.

Results: After a median follow-up of 25 months, LTP occurred in 18 HCCs (40%) and 18 patients (42.9%). Multivariate competing risk regression comprising ΔNLR_1stFU > 0, cirrhosis etiology and subcapsular location showed that the only independent predictor of LTP was ΔNLR_1stFU > 0, on both a per-patient (HR = 2.7, p = 0.049) and per-tumor (HR = 2.8, p = 0.047) analysis. ΔNLR_1stFU > 0 occurred in 24/42 patients (57.1%). In this subgroup, higher rates of female patients (p = 0.026), higher mean baseline NLR (p < 0.0001) and lower mean energy/size (p = 0.006) were observed. Upon ROC curve analysis, energy/size < 1414 J/mm predicted ΔNLR_1stFU > 0 with 76% sensitivity and 70% specificity (AUC = 0.74).

Conclusion: NLR increase after ablation was the only independent predictor of LTP, supporting the role of balance between systemic inflammation and immunity in recurrence after MWA. Ablation energy/tumor size predicted NLR increase, reinforcing the concept of immune ablation.

Level of evidence: III.

Keywords: Adaptive immune response; Hepatocellular carcinoma; Inflammation; Microwave; NLR; Thermal ablation.