title: Histological type of Thorotrast-induced liver tumors associated with the translocation of deposited radionuclides.
abstract: Exposure to internally deposited radionuclides is known to induce malignant tumors of various histological types. Thorotrast, a colloidal suspension of radioactive Thorium dioxide ((232)ThO(2)) that emits alpha-particles, was used as a radiographic contrast during World War II. Thorotrast is known to induce liver tumors, particularly intrahepatic cholangiocarcinoma (ICC) and angiosarcoma (AS), decades after injection. Therefore, patients injected with Thorotrast comprise a suitable study group to understand biological effects of internal ionizing radiation injury. Autoradiography and X-ray fluorescence spectrometry (XRF) were carried out on non-tumorous liver sections from Thorotrast-induced ICC (T-ICC) and Thorotrast-induced AS (T-AS). Autoradiography revealed that the slope of the regression line of the number of alpha tracks for the amount of deposited Thorium ((232)Th) was higher in non-tumorous parts of the liver with T-ICC than those with T-AS. XRF showed that the intensity ratio of Radium (Ra) to Thorium (Th) in non-tumorous liver tissue with T-ICC was significantly higher than that with T-AS. Furthermore, the mean (228)Ra/(232)Th radioactivity ratio at the time of death calculated was also significantly higher in T-ICC cases than in T-AS cases. These suggest that the metabolic behavior of radionuclides such as relocation and excretion, as well as the content of deposited radionuclides, is a major factor in determining the histological type of Thorotrast-induced liver tumors.
authors.affiliation: Department of Pathology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Junichi
authors.initials: J
authors.lastname: Chikawa
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Uegaki
authors.forename: Nobuteru
authors.initials: N
authors.lastname: Usuda
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kuwahara
authors.forename: Manabu
authors.initials: M
authors.lastname: Fukumoto
mesh_terms: D000328:Adult; D000512:Alpha Particles; D001345:Autoradiography; D001692:Biological Transport; D006801:Humans; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D011829:Radiation Dosage; D011883:Radium / Q000493:pharmacokinetics*; D013052:Spectrometry, X-Ray Emission; D013910:Thorium / Q000493:pharmacokinetics*; D013911:Thorium Dioxide / Q000009:adverse effects*
chemical_list: D013910:Thorium; D013911:Thorium Dioxide; D011883:Radium