A study recently published in the British journal The Lancet has caused a great stir among parents concerned about its conclusion that CT scanning significantly increases the risk of leukemia and brain tumors in children. For the record, that’s exactly what the study shows, but let’s give the finding some much-needed perspective.
The investigators examined brain cancer and leukemia rates in Great Britain in people younger than 22 who received CT scans between 1985 and 2002 for reasons having nothing to do with a cancer diagnosis. (Why brain cancer and leukemia? Because the brain and bone marrow–where leukemia arises–are the most radiosensitive tissues, particularly in children.) The researchers then compared these rates to those in young people who were not scanned during this period, and they found that a dose of about 50 to 60 mGy (approximately twice the average radiation dose of a CT scan during those years) tripled the risk of leukemia and brain tumors.
What’s the Real Risk?
However, let’s take a deep breath and look at the absolute numbers: Only 74 out of more than 175,000 people developed leukemia, and only 135 developed a brain tumor. Upon further examination of these numbers, the researchers were able to conclude that in the youngest patients–those younger than 10–there would be 1 excess case each of leukemia and brain cancer for every 10,000 head CTs!
Notably, head CTs have, by far, the highest radiation dose of any type of CT scan. Therefore, the risk, although real, is very, very low. In addition, CT scanning today uses significantly lower doses of radiation than even just a decade ago.
Understand the Risk, Consider Your Options
So what should you do with this information? If your doctor recommends a CT scan for your child, make sure it’s the right test for your child, and the only one that can provide the information your doctor needs. If another test will suffice, or if the CT isn’t really necessary at all, then consult your health care provider to discuss an alternate route. However, if the CT is truly necessary and there is no good alternative, you can feel confident that the risk is tiny and is likely far outweighed by the risk of not getting an essential study. As always, be an informed and appropriately concerned consumer of medicine.