Open AccessHistological type of Thorotrast‐induced liver tumors associated with the translocation of deposited radionuclides
Author(s) -
Yamamoto Yoichiro,
Chikawa Junichi,
Uegaki Yoshinobu,
Usuda Nobuteru,
Kuwahara Yoshikazu,
Fukumoto Manabu
Publication year - 2010
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/j.1349-7006.2009.01401.x
Subject(s) - thorotrast , thorium dioxide , nuclear medicine , thorium , pathology , chemistry , medicine , radiochemistry , uranium , materials science , nuclear chemistry , metallurgy
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. ( Cancer Sci 2009)