Dynamic Lymphocyte Changes Following Transarterial Radioembolization: Association with Normal Liver Dose and Effect on Overall Survival.

OBJECTIVE: To evaluate the dynamic changes of lymphocytes following transarterial radioembolization (TARE) for hepatocellular carcinoma (HCC) and their relationship to normal liver dose (NLD). MATERIALS AND METHODS: A total of 93 patients who underwent 102 treatments were retrospectively reviewed. Absolute lymphocyte counts pretreatment and at 1, 3, 6, and 12 months were evaluated. Kaplan-Meier, Spearman correlation, receiver operating characteristic (ROC) curve, and area under the curve (AUC) analyses were performed. RESULTS: The mean absolute lymphocyte count at baseline was 1.25 ± 0.79 103/µL which was significantly greater than 1 (0.71 ± 0.47 103/µL, p<0.0001), 3 (0.79 ± 0.77 103/µL, p=0.0003), and 6 (0.81 ± 0.44 103/µL, p=0.0001) months, but not significantly different than 12 (0.92 ± 0.8 103/µL, p=0.12) months post treatment. There was a modest negative correlation between NLD and lymphocyte count at 1 month (rho= -0.216, p=0.03), which strengthened at 3 months post treatment (rho= -0.342, p=0.008). AUC of ROC analysis between absolute lymphocyte count ≤1 103/µL or >1 103/µL at 1, 3, 6, and 12 months post treatment was 0.625, 0.676, 0.560, and 0.794, respectively. Univariate analysis of overall survival when separating patients by a lymphocyte count of ≤1 103/µL and >1 103/µL demonstrated a significant difference at 1 (HR: 0.56, 95% CI: 0.33-0.95, p=0.03), 3 (HR: 0.41, 95% CI: 0.18-0.94, p=0.035) and 6 (HR: 0.36, 95% CI: 0.17-0.77, p=0.008) months post treatment, but not pretreatment or at 12 months. CONCLUSION: NLD may correlate with lymphocyte depression at 1 and 3 months and lymphopenia may portend a worse overall survival in the post treatment setting.