Long term mortality after a single treatment course with X-rays in patients treated for ankylosing spondylitis

Abstract

Summary Mortality up to 1 January 1983 has been studied in 14,106 patients with ankylosing spondylitis given a single course of X-ray treatment during For leukaemia there was a threefold increase in mortality that is also likely to have been due to the radiotherapy. The relative risk was at its highest between 2.5 and 4.9 years after the treatment and then declined, but the increase did not disappear completely, and the risk was still nearly twice that of the general population more than 25.0 years after treatment. There was some evidence that the risks of acute myeloid, acute lymphatic, and chronic myeloid leukaemia were all increased, but no evidence of any increase in chronic lymphatic leukaemia. The relative risk appeared to be greatest for acute myeloid leukaemia.For colon cancer, which is associated with spondylitis through a common association with ulcerative colitis, mortality was increased by 30%.For non-neoplastic conditions there was a 51% increase in mortality that was likely to be associated with the disease itself rather than its treatment. (Court Brown & Doll, 1965) and related the incidence of leukaemia to the dose received. These analyses included many patients who had been treated with X-rays for their spondylitis more than once and it was not clear whether the increase that continued for many years should be attributed to the first or subsequent courses. When Smith & Doll (1978;1982) reported on the follow-up of the patients to 1970, they avoided this difficulty by restricting the analyses to patients who had received only a single course of treatment. Their analyses showed that, when the mortality of the spondylitic patients was compared with that of the general population, the relative risk of leukaemia was at a maximum 3-5 years after treatment and subsequently declined. For other cancers of sites judged to be heavily irradiated, the relative risk was at a maximum 9-11 years after treatment and then declined to less than one after 24 years. Only a small proportion of patients had been followed beyond 20 years, however, and the decreasing trend in relative risk for these other cancers more than 11 years after treatment was not statistically significant. We have, therefore, sought to find out how long the increased mortality from leukaemia and other cancers persisted following X-ray treatment by extending the follow-up of patients who received only a single course of treatment by a further 13 years and have related the increased mortality to organ dose. We report here only the data for total and organ specific mortality and have deferred discussion of the complex relationship with dose to a later report. Material and methodsStudy population andfollow-up

Intérêt et limites de l'épidémiologie pour l'évaluation des risques de cancers radioinduits et l'établissement des normes de radioprotection

“…Au Royaume Uni, 14 000 personnes irradiées pour une spondylarthrite ankylosante ont été très régulièrement suivies et cette population a également permis d'établir des calculs précis de risque de leucémie ou de cancers secondaires [13,39]. Une nouvelle estimation des doses absorbées aux différents organes devrait accroître la fiabilité des évaluations de risque pour cette cohorte [25].…”

“…Trois populations irradiées regroupant un nombre très important de personnes suivies pendant de nombreuses années ont été choisies pour évaluer le risque cancérigène des rayonnements. Outre les survivants japonais d'Hiroshima et Nagasaki [37], deux groupes de patients sont considérés: britanniques irradiés pour spondylarthrite ankylosante [13] -Dans le cas des spondylarthrites et des cancers du col, ces coefficients sont ceux communiqués par les auteurs. Les calculs ont été effectués pour la population dans son ensemble ainsi que la population au travail (entre 25 et 64 ans).…”

A Model for Dose Rate and Duration of Exposure Effects in Radiation Carcinogenesis

“…These data have provided great insight into the form of the dose-response relationship and the modifying effects of age at exposure and time since exposure, but obviously no data on the effect of duration of exposure. Although some of the patients treated for ankylosing spondylitis received several courses of treatment, analyses that have been published to date have been restricted to those receiving a single course (15 Although analyses within some of these cohorts may be helpful, they are unlikely to provide very powerful tests of the model. There are, however, a large number of animal experiments that have addressed the effect of dose-rate and duration for both low-and high-LET radiation (18)(19)(20).…”

Radiation-Induced Lung Cancers in Murine Models

“…Three groups have been historically responsible for the majority of data on the contribution of radiation exposure to lung carcinogenesis. These groups are 1) underground miners, exposed to internal alpha radiation via radon-222 and radon-220 inhalation; 2) Patients who have undergone radiotherapy patients to treat neoplastic and nonneoplastic malignancies, and 3) Japanese atomic bomb survivors [13]- [15]. The latency period for gamma and X-ray exposed individuals seems to be a minimum of 9 -10 years, with an increased risk persisting in survivors for over 25 years.…”