Malignancies in patients treated with high doses of radium-224

Several thousand German patients suffering from ankylosing spondylitis, tuberculosis and some other diseases, received multiple injections of the short-lived α-emitter 224Ra. The ''Spiess study'' was initiated in the early 1950s to follow the health of 899 persons (278 female, 621 male) who were treated mainly between 1945 and 1955. Most of the high dose patients and nearly all of those treated as children or juveniles (n=217) were included in the study. In June 2003, 152 persons were still alive. The most striking observed health effect, following 224Ra injections, was a temporal wave of 56 malignant bone tumours with a maximum at about 8 years after exposure which has already been described in several publications. In 2000, a new analysis was performed because an improved dosimetry resulted in modified bone surface doses. The estimated risk coefficient, averaged over all ages at exposure, was found to be in agreement with earlier analyses. However, a statistically significant increase of bone tumour risk with decreasing age at exposure was found. The earlier results, which indicated a reversed protraction factor, were confirmed. A significant excess of non-skeletal solid malignancies has also appeared during the most recent observation decade. In 2004, significant increases of cancer rates were observed for several sites: for breast cancer (31 cases observed vs. 9.1 cases expected), soft tissue malignancies (11 vs. 1.0), thyroid carcinomas (7 vs. 0.9), liver (8 vs. 2.3), kidney (13 vs. 4.6), pancreas (8 vs. 3.9), and bladder cancer (14 vs. 7.7). The 8-fold excess relative risk of mammary cancers in those women exposed as children or juveniles is particularly striking; moreover, 2 cases of breast cancer occurred in men. In 1993, a control group of tuberculosis patients not treated with 224Ra was established to rule out potential confounding factors - such as chest fluoroscopy - which might bias the breast cancer excess. From the comparison it appeared, that the 224Ra treatment is responsible for most of the mammary cancer excess. (orig.)