Limited cancer risk from radiation in pregnancy
Wednesday September 8th, 2010
Researchers are investigating the possible childhood cancer risk from foetal exposure to radiation.
Dr Joel Ray of St Michael's Hospital in Toronto, Ontario, Canada, and colleagues say the cause of most childhood cancers is unknown. They point out that there has been a substantial increase in the use of computed tomography (CT) and radionuclide imaging, making them a common source of radiation to pregnant women.
"There may be an association between exposure to ionising radiation in pregnancy and childhood cancer," they write in the journal PLoS Medicine.
The team analysed figures on 1.8 million mother-child pairs between 1991 and 2008. Of these, 5,590 mothers were exposed to major radiodiagnostic testing in pregnancy, with the rate increasing over time.
After a follow-up of around nine years, 2,543 childhood cancers were diagnosed in total. The risk was 1.13 per 10,000 person-years in the exposed group and 1.56 per 10,000 person-years in the unexposed group.
The experts conclude: "The absolute annual risk of childhood malignancy following exposure in utero remains about 1 in 10,000."
But they add that very few cancers occurred in the exposed group in this study, so "we cannot exclude the possibility that foetal exposure to CT or radionuclide imaging is carcinogenic".
They recommend that beta hCG testing (a pregnancy blood test) should continue to be done in all potentially pregnant women before undergoing major radiodiagnostic testing, and lead apron shielding of the pelvic area of pregnant women should be used.
Commenting on the study, Dr Eduardo Franco of McGill University, Montreal, Canada, say it "raised the bar substantially for future large-scale studies" by showing how record linkage of multiple databases can be used to calculate disease risk.
Franco, E. L. and Turgeon, G-A. Radiodiagnostic Imaging in Pregnancy and the Risk of Childhood Malignancy: Raising the Bar. PLoS Medicine, 2010, 7(9): e1000338.
Tags: Cancer | Child Health | Childbirth and Pregnancy | North America | Women’s Health & Gynaecology
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