Prenatal x‐ray exposure and childhood cancer in swedish twins

Publisher Website
Google Scholar
Abstract
The association between X‐ray exposure in utero and child hood cancer was studied in a case‐control study, nested in a national cohort of Swedish twin births. Records of the Swedish Twin Register for those born 1936‐1967 (n = 83,316) were linked to the Swedish Cancer Register (1958‐1983) and the Swedish Cause‐of‐Death Register (1952‐1983). Ninety‐five cases of childhood cancer before the age of 16 were identified. Two controls from the Twin Register were matched to each case by sex and year of birth. Maternal X‐rays during preg nancy were documented for 41% of the cases and 36% of the controls. The crude relative risk of any childhood cancer associated with any prenatal X‐ray was 1.2 (95% CI; 0.7‐2.1). For the cases 64% of the X‐rayed women had had abdominal X‐rays, the numbers for the controls were 57%. Fifty‐nine per cent of the X‐rayed women had had abdominal X‐rays, which were associated with a relative risk for all cancers of 1.4 (Cl; 0.8‐2.5), leukemias I.7(CI; 0.7‐4.1) and tumors of the central nervous system 1.5 (Cl; 0.5‐4.2). There was no apparent confounding by mother's age, drug use, obstetric complications, previous miscarriages, social class or length of pregnancy. The observed relative risks of cancer following prenatal X‐ray ex posure are consistent with previous studies, suggesting that the developing fetus may be more sensitive to the carcinogenic effects of ionizing radiation than are children irradiated post‐natally.