Breast Cancer Risk 55+ Years After Irradiation for an Enlarged Thymus and Its Implications for Early Childhood Medical Irradiation Today

Abstract

Background: Radiotherapy during childhood increases long-term cancer risk, but the risk from radiation as a result of relatively higher dose diagnostic procedures remains less well known. This study, which evaluates breast cancer incidence in a cohort treated with "lower dose" chest radiotherapy over 50 years ago, can assist with estimating lifetime breast cancer risk in young children exposed to radiation from procedures such as chest computed tomography (CT) or treatment with recent "lower dose" chest radiotherapy protocols.Methods: A population-based, longitudinal cohort of subjects exposed to thymic irradiation during infancy from 1926 to 1957 and of their unexposed siblings was re-established. Previously followed until 1987, we resurveyed cohort members from 2004 to 2008. Poisson regression models compared breast cancer incidence rates between women in the cohort by treatment and dose category groups.Results: Breast cancer occurred in 96 treated (mean breast dose, 0.71 Gy) and 57 untreated women during 159,459 person-years of follow-up. After adjusting for attained age and treatment/birth cohort, the rate ratio was 3.01 (2.18-4.21). The adjusted excess relative risk per Gy was 1.10 (95% confidence interval, 0.61-1.86). Traditional breast cancer risk factors did not contribute significantly to multivariate model fit.Conclusion: Our results show that at radiation doses between those received by the breast from chest CT and cancer therapy during early childhood, breast cancer incidence rates remain elevated >50 years after exposure. This implies that increased breast cancer risk will remain a lifelong concern in females treated during childhood with currently reduced radiotherapy doses and for infants receiving multiple chest CTs. Cancer Epidemiol Biomarkers Prev; 19(1); 48-58. ©2010 AACR.

New dosimetry for childhood skin hemangioma treatments with 226Ra needles or tubes

“…In the French study the breast and thyroid doses are lower, 0.070 Gy [13] and 0.041 Gy [14] respectively, which might depend on their use not only of 226 Ra applicators but also some b emitters. In the thymus study where the children had been exposed to X-ray radiation toward the chest, the updated breast and thyroid doses are higher, 0.71 Gy [15] and 1.29 Gy [16] respectively, than in our study. For epidemiological studies in children exposed to ionizing radiation because of benign conditions these studies remain for the time being our main sources for evaluation of radiation risk estimates.…”

Fetal Irradiation of Rats Induces Persistent Translocations in Mammary Epithelial Cells Similar to the Level after Adult Irradiation, but not in Hematolymphoid Cells

“…Specifically, after radiation exposure in infancy, increased risk levels were observed in studies of patients treated with radiation for hemangioma (24) or enlarged thymus (25,26) and in studies of individuals exposed to A-bomb radiation (6,27). After fetal exposure, however, even the total cancer risk is not well established in the A-bomb survivors because the epidemiologic cohorts of A-bomb survivors are fairly small and the number of subjects with known doses is about 2,500 TRANSLOCATION INDUCTION AFTER FETAL IRRADIATION OF RATS (28,29).…”

Frequent MUGA testing in a myeloma patient: A case-based ethics discussion

“…3,13 The management discussion of this case requires consideration of several complex issues: (i) The need for therapy-specific monitoring guidelines; (ii) Recognition of differences in accuracy, reproducibility of LVEF; patient acceptance; and the need for evidence-based outcome effectiveness of non-radionuclide candidate techniques such as 3D echo without contrast and CMR with LVEF variance of \5% to permit identification of real decline of LVEF [ 10 EF units to baseline EF determined EF targets 7 ; (iii) New questions of safety of CMR have been raised by the report of CMR-induced phosphorylation of DNA-damage marker proteins observed at day 2 to 30 after exposure 14 ; (iv) Recognizing cancer risk with diagnostic levels of radiation with fractionated dosing of serial MUGAs remains theoretical and with orders of magnitude less likely than HF risk associated with complex, intensive chemotherapy; (v) At 113 mSv cumulative dose, this patient has been exposed to slightly more than the 100 mSv ''lowlevel radiation'' threshold which remains substantially below the very low lifetime risk of oncogenesis reported for therapeutic radiation exposure. 15,16 Baseline MUGA prior to cancer therapy and subsequent studies alternating MUGA and echocardiograms may be a reasonable alternative strategy in this patient.…”