Childhood and adult cancer after intrauterine exposure to ionizing radiation

Abstract

Since the reports in 1956 and 1958 that in utero radiation was associated with an increased risk of leukemia and solid cancers during childhood, this issue has been debated. Many epidemiological studies have been performed. Evidence for a causal association derives almost entirely from case‐control studies, whereas practically all cohort studies find no association, most notably the series of atomic bomb survivors exposed in utero. Although it is likely that in utero radiation presents a leukemogenic risk to the fetus, the magnitude of the risk remains uncertain. The causal nature of the risk of cancers other than leukemia is less convincing, and the similar relative risks (RR = 1.5) for virtually all forms of childhood cancer suggests an underlying bias. Few studies have addressed the potential risk of adult cancer after intrauterine exposure. Radiotherapy given to newborns, however, has been linked to cancers of the thyroid and breast later in life. Teratology 59:227–233, 1999. © 1999 Wiley‐Liss, Inc.

The cancer epidemiology of radiation

“…A causal explanation of this association is not universally accepted (Boice and Miller, 1999), but Doll and The cancer epidemiology of radiation R Wakeford Wakeford (1997) concluded that the evidence strongly suggests an underlying cause-and-effect relationship. Recently, Wakeford and Little (2003) showed that the ERR coefficient that may be derived from the largest case-control study of childhood cancer and obstetric radiographic examinations (the OSCC) is consistent with the estimate obtained from the Japanese atomic bomb survivors irradiated in utero who received, on average, doses an order of magnitude higher, although the uncertainties associated with this comparison imply that any inference of linearity can only be tentative.…”

Counseling patients exposed to ionizing radiation during pregnancy

“…Even if one accepts the controversial concept that the embryo is more sensitive to the carcinogenic effects of radiation than the child is, the risk at these low exposures is much smaller that the spontaneous risks (Table 1). Furthermore, other studies (16)(17)(18) indicate that the estimate of the risk of radiation-induced leukemogenesis made by Stewart et al (15) is exaggerated. Table 1 presents the spontaneous risks facing an embryo at conception and the additional risks that would come from a low exposure of ionizing radiation (0.05 Gy).…”

“…However, when the exposure exceeds the threshold dose, the risks of radiation exposure to the human embryo include embryonic loss, growth retardation, congenital malformations, microcephaly and mental retardation, infertility, and carcinogenesis (with the magnitude of the oncogenic risk to the fetus being controversial) (15)(16)(17)(18).…”

“…However, if they are concerned about cancer, it is primarily a concern about childhood leukemia. The risk of leukemia following fetal exposures from diagnostic radiological studies is a small fraction of the spontaneous leukemia risk, even when the risk published by Wakeford and Little (18) is utilized, and the risks estimated by other investigators (16)(17) are lower than those of Wakeford and Little.…”

Preface

“…These well established risk factors, i.e., family history, reproductive and menstrual history, and history of benign breast disease, are estimated to account for only about 40 % of breast cancer cases [17]. Childhood exposure to ionizing radiation [18][19][20], adult alcohol consumption [21], and obesity [7,22,23] also increase the risk of developing breast cancer. However, these risk factors are unlikely to account for the remaining cases of the disease [2,7,24] suggesting that there are still unidentified causes of breast cancer.…”