Therapeutic effects of transarterial infusion of lipiodol and ethanol in various ratios in a rabbit VX2 tumor model.

PURPOSE We aimed to evaluate the therapeutic effect and safety of transcatheter arterial embolization with various volume ratios of lipiodol and ethanol in a rabbit VX2 tumor model to identify the optimal volume ratio. METHODS Eighteen adult male New Zealand white rabbits implanted with VX2 tumors in their left liver lobes were randomly divided into six groups based on volume ratios of lipiodol to ethanol: group A, 3:1; group B, 2:1; group C, 1:1; group D, 1:2; group E, 1:3; and group F, 1:4. Pre- and post-treatment unenhanced magnetic resonance imaging was used to detect tumor formation and evaluate tumor growth rates. Liver samples were harvested one week after the procedure, and apoptosis index of tumor tissues was evaluated by pathologic examination and TUNEL assay. RESULTS Tumor size decreased in groups B, C, and D, but increased in groups A, E, and F. Tumor growth rates in groups A-F were 0.40±0.03, -0.11±0.21, -0.08±0.09, -0.12±0.07, 0.06±0.12, and 0.05±0.09, respectively. The change in tumor size was significantly different in group A compared with the rest of the groups, but no significant difference was observed among groups B-F. Apoptosis indexes of the six groups were 4.7±2.1%, 6.7±2.1%, 11.7±3.1%, 11.0±2.0%, 10.7±3.2%, and 12±3%, respectively. Apoptosis index was significantly lower in group A compared with groups C-F (P < 0.05). Apoptosis index of group B was significantly lower than groups C and F. There was no significant difference among the other groups. CONCLUSION The volume ratios of lipiodol to ethanol ranging from 2:1 to 1:4 were equally effective, the ratios 2:1 and 1:3 had equal safety, and the ratios 1:1 and 1:2 indicated better long-term therapeutic effect. Increasing ethanol in the mixture caused more severe liver injury. Optimal efficacy and safety was achieved with a lipiodol to ethanol volume ratio of 1:1.