NEUHERBERG, Germany—Ankylosing spondylitis (AS) patients who were treated with repeated intravenous injections of 224Radium (SpondylAT®) are at increased risk for developing leukemia, according to a new study in Rheumatology.1 In fact, the results of these studies contributed to 224Radium preparations being declared obsolete and resulted in the revocation of the licensing of SpondylAT by the Federal Institute for Drugs and Medical Devices and the decision by the license holders to discontinue developing the treatment.

"The enhanced leukemia incidence in the exposed group is in line with results from experiments in mice injected with varying amounts of the bone-seeking α-emitter 224Radium."—Roland R. Wick, MD
"The enhanced leukemia incidence in the exposed group is in line with results from experiments in mice injected with varying amounts of the bone-seeking α-emitter 224Radium," concluded researchers led by Roland R. Wick, MD, of the German Research Center for Environmental Health in Neuherberg.

In the new study, researchers tracked 1471 AS patients who were treated with repeated intravenous injections of 224Radium, which has a known analgesic effect. They compared the cancer rates with that of a control cohort of 1324 AS patients who were not treated with radioactive compounds and/or X-rays.

Overall, there were 19 cases of leukemia diagnosed among AS patients treated with 224Radium, compared with 6.8 cases that would be expected in an age- and gender-matched cohort of a normal population. In particular, the incidence of acute myeloid leukemia was significantly increased with 7 cases in the 224Radium group compared with 1.8 cases expected in the general population. In addition, there were four more cases of preleukemic diseases of the bone marrow in the exposed group and no cases were in the control group. The frequency of leukemia was not increased significantly in the control group compared with the expected value for a normal population, the study showed.

"It is rather unlikely that impurities present in the radium preparations used before 1950 are responsible for the elevated appearance of myeloproliferative diseases in the exposed group observed here," Dr. Wick said.

Reference
1. Wick, RR, Nekolla, EA, Gaubitz M, et al. Increased risk of myeloid leukaemia in patients with ankylosing spondylitis following treatment with radium-224. Rheumatology. 2008;47:855-859.