A cytotoxic radioconjugate consisting of ethiodized oil, an iodinated ethyl ester derived from poppy seed oil, labeled with iodine 131 (I-131). Iodine I 131 ethiodized oil accumulates in hepatocellular carcinoma and hepatoblastoma tumor cells, resulting in targeted cytotoxicity to tumor cells while sparing surrounding normal cells and tissues. Check foractive clinical trials using this agent. or A radioactive substance being studied in the treatment of liver cancer. It is a form of poppy seed oil that contains iodine, some of which is the radioactive substance iodine I 131. It builds up in the blood and lymph vessels in the liver and may kill cancer cells. It is a type of radiopharmaceutical. Also called iodine I 131 Lipiodol.