Cutoff Values for Dose-liver Function Parameters to Prevent Radiation-induced Liver Disease in Advanced Hepatoma

Abstract

AIM: To retrospectively explore the cutoff values that predict radiation-induced liver disease (RILD) in hepatocellular carcinoma (HCC) patients with portal vein tumor thrombus (PVTT) in the main trunk and/or the first branch who had previously received single-photon-emission computed tomography (SPECT)-based three-dimensional conformal radiotherapy (3DCRT; SPECT-B-3DCRT) using Tc-99m-galactosyl human serum albumin (Tc-99m GSA). METHODS: Seventy-five HCC patients with PVTT underwent SPECT-B-3DCRT (total dose of 45 Gy/18 fractions) in the stop-breathing position with an error of ≤ 5 mm. SPECT allowed the minimum possible irradiation of the functional liver (FL). Child–Pugh score deterioration (CPSD) by 2 (= RILD) or CPSD by 1 was scored within four months of completing SPECT-B-3DCRT. Receiver-operating characteristic (ROC) analysis of the outcomes RILD vs CPSD by 1 was conducted to determine the accuracy and cutoff values for FLV20Gy (percentage of FL volume receiving ≥ 20 Gy), F20Gy (GSA counts within the irradiated liver area receiving ≥ 20 Gy × 100/GSA counts in the whole liver), F20Gy/LHL15 (liver radioactivity counts at 15 min/heart plus liver radioactivity counts at 15 min), and F20Gy/total count ratio (liver radioactivity counts/liver plus total background radioactivity counts). RESULTS: The cutoff values and accuracy of FLV20Gy, F20Gy, F20Gy/LHL15, and F20Gy/total count ratio were 26.4 and 0.826 (p=0.024), 30.2 and 0.913 (p=0.004), 37.7 and 0.913 (p=0.001), and 43.0 and 0.957 (p<0.001), respectively. CONCLUSION: An F20Gy/total count ratio of 43.0 is the most reliable cutoff value for preventing RILD.