Targeting liver tumors with hyperthermia: Ferromagnetic embolization in a rabbit liver tumor model

Background and Objectives: Ferromagnetic embolization hyperthermia (FEH) co nsists of arterially embolizing liver tumors with ferromagnetic particles, and then applying an external alternating magnetic field to generate hyster etic heating within the embolized particles. The objective of this study wa s to assess the ability of FEH to selectively target liver tumors with hype rthermia. Methods: Twenty rabbits containing hepatic VX2 carcinomas were arterially i nfused with ferromagnetic particles suspended in lipiodol, and then exposed to an external alternating magnetic field. Temperatures in the tumor, norm al hepatic parenchyma (NHP), and rectum were recorded. Tumour and NHP were chemically analyzed for iron content, which was then correlated with the ob served heating rates. Results: The mean tumor-to-NHP iron concentration ratio was 5.3:1 (P < 0.00 1, N = 20). The mean tumor heating rates were 3.0-11.5 times greater than t hose in the NHP (P < 0.00 1, N = 20). After 5 min of heating, the greatest increase in mean tumor temperature was 11.0<degrees>C and the greatest incr ease in mean NHP temperature was 1.3 degreesC. There was a positive relatio nship between tumor iron concentration and heating rate (correlation coeffi cient = 0.82, P < 0.00 1, N = 20). A tumor iron concentration of 2-3 mg/g r esulted in tumor heating rates of 0.5-1.0 degreesC/min. Conclusions: Hepatic arterial infusion of lipiodol containing ferromagnetic particles can result in excellent targeting of liver tumors with hyperther mia on the subsequent application of an external alternating magnetic field . The promising results of this study warrant further investigation of FEH as a potential treatment for advanced liver cancer. (C) 2001 Wiley-Liss, In c.