Japanese patients with leukaemia following the use of Thorotrast including a patient with marked chromosomal rearrangements.

It is estimated that 20,000-33,000 persons have been injected with Thorotrast in Japan. By August 1984, 12 patients with leukaemia following the use of Thorotrast have been reported. Their clinical and haematological data indicate that most of the patients were males over 50 years of age and that the most frequent type of leukaemia involved the stem cells common to the granulocytic, erythroid and/or megakaryocytic lines. This assumption was supported by the evidence of marked chromosomal rearrangements in 100% of the cells from the bone marrow in our case. The median latent period from the administration of Thorotrast to the onset of leukaemia in Japan was 35 years, ranging from 16 to 45 years, which indicates that patients who were injected with Thorotrast should be carefully followed up in the future.