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 10(3)/µL which was significantly greater than 1 (0.71 ± 0.47 10(3)/µL, p<0.0001), 3 (0.79 ± 0.77 10(3)/µL, p=0.0003), and 6 (0.81 ± 0.44 10(3)/µL, p=0.0001) months, but not significantly different than 12 (0.92 ± 0.8 10(3)/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 10(3)/µL or >1 10(3)/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 10(3)/µL and >1 10(3)/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.