Mortality among patients with ankylosing spondylitis after a single treatment course with x-rays

Court Brown and Doll identified over 14,000 patients with ankylosing spondylitis who had been treated with one or more courses of x-irradiation from 1935 to 1954 at one of 87 radiotherapy centers in Great Britain and Northern Ireland. The first reports from this study analyzed mortality among these patients from leukemia and other causes, particularly cancer, but these analyses included many patients who had been treated with x-rays for their spondylitis more than once. This complicated the interpretation of the late effects of the treatment on mortality, as it was not clear to what extent the subsequent treatments contributed to the excess of deaths that persisted for many years after the first treatment. Smith and Doll (1982) avoided this difficulty by examining the death rate from leukemia and other radiation-induced cancers at different times after a single course of treatment. A comparison of the mortality of this group with the mortality of Japanese atomic bomb survivors revealed good agreement between the two studies, thus increasing confidence in the belief that both studies are giving sensible estimates of the risk of cancer from high doses of radiation. The follow-up of those spondylitic patients who received a single course of treatment only has recently been extended until the end of 1982, that is, for an additional 13 years. A further 1406 patients are now known to have died, including an additional 335 deaths for which the certified cause is cancer. Detailed results of this further follow-up will be presented