Changes in peripheral blood T-cell balance after percutaneous tumor ablation

To evaluate the changes in T-cell balance in peripheral blood following percutaneous tumor ablation.

Patients underwent thermal ablation including radiofrequency (n = 9) and microwave ablation (n = 5), or cryoablation (n = 5). Target tumors were located in the lung (n = 7), soft tissue (n = 5), liver (n = 4), and bone (n = 3). Patient peripheral blood samples were collected before and within 14 days after ablation. Peripheral blood populations of cytotoxic T-cells (CTL), type-1 (T_h1) and type-2 helper T-cells (T_h2), and regulatory T-cells (T_reg) were measured using flow cytometry. Changes in CTL/T_reg and T_h1/T_h2 ratios before and after ablation therapy were compared using paired t-tests.

Peripheral blood CTL population (27.5 ± 2.1% to 30.2 ± 2.5%, p < .03) and CTL/T_reg ratios (18.8 ± 3.7% to 21.6 ± 3.6%, p < .05) increased significantly after ablation. Although a significant increase in CTL/T_reg ratios was found after heat-based ablation (18.0 ± 4.4% to 21.6 ± 4.7%, p < .02), it remained unchanged after cryoablation (21.0 ± 7.0% to 21.5 ± 4.3%, p = .92). T_h1/T_h2 ratio (13.7 ± 3.0% to 17.2 ± 3.5%, p = .12) remained unchanged after ablation.

Ablation therapy alters the T-cell balance by increasing the systemic CTL/T_reg, ratio. Heat-based ablation might be a more effective approach than cryoablation to enhance systemic anti-tumor immunity.