The German Thorotrast study comprises 2,326 patients and 1,890 controls. Fo
rty-eight Thorotrast patients and 239 controls are still alive and are invi
ted far a follow-up examination every 2 years. In the deceased patients, th
e following neoplastic diseases with excess rates were registered (Thorotra
st/controls): liver cancer (454/3); cancer of the bile ducts, including gal
lbladder (42/7); myeloid leukemia (40/7); myelodysplastic syndrome (30/4);
plasmacytoma (10/2); nonHodgkin's lymphoma (15/5); bone sarcoma (4/1); mali
gnant peritoneal or pleural mesothelioma (9/0). Dose calculations are based
on results of whole-body counting, X-ray films, and data obtained from the
hospital records on the volume of Thorotrast injected. For liver canter, t
he cumulative risk estimate was calculated to be 40 per 10(4) person Sv (ra
diation weighting factor = 20). These figures are close to the results of t
he Danish study and are comparable to the results of the Life Span Study of
A-bomb survivors after 40 years at risk with 18 to 48 liver cancers per 10
(4) person Sv. For hematopoietic malignancies, the cumulative risk was calc
ulated to be about 7 per 10(4) person Sv (radiation weighting factor = 20).
This risk estimate is lower by a factor of 10 compared to the results of t
he Life Span Study. (C) 1999 by Radiation Research Society.