Weighing the risks and benefits of CT scans in childhood - and the implications for adult scans

Weighing the risks and benefits of CT scans in childhood - and the implications for adult scans

While thankfully, CLL specialists are now recommending significantly less use of CT scans for monitoring CLL than has historically been the case, those of us in clinical trials can have little to no choice in the number of scans required. For those that are concerned about the increased risk of cancer from CT scan radiation, this article by John Mathews, Honorary Professorial Fellow, University of Melbourne, may provide some reassurance:

'In a recent study of almost 11 million young Australians, we showed that those exposed to a CT scan before the age of 20 had a small increase in cancer risk in the years after exposure, with one additional cancer for every 1,400 to 2,000 CT scans.

So this means one CT scan would increase the possibility of a later cancer, but only by a very small amount - the absolute risk of an “extra” cancer for an exposed person is presently about one in 1,400 to one in 2,000. And it would not be possible to say, in a person who does get a cancer in the years after a CT scan, whether it was due to the CT or whether it would have occurred anyway.


For adults and older patients, CT scans are used more frequently than for children, and cancer rates increase with age, even without radiation. This suggests that for older individuals the benefit to risk ratio for CT scans is better than for children.

Nevertheless, because of the relatively high usage rates of CT scans in Australia, there is scope to reduce the numbers of unnecessary scans for adults as well as children. Accordingly, adult patients should also query whether each and every suggested CT scan is justified by the relevant clinical guidelines.'

Full article:


BMJ Paper:

Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians bmj.com/content/346/bmj.f23...

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9 Replies

  • I recall one CLL doc at MDAnderson noting that there may be too many scans in trials but the FDA requires it. One trial I considered required 8 scans I believe. Too much for my taste.

  • Thanks for the post Neil.

    You may have just read (Newdawn's post re pneumonia jabs) that I have had two CT scans in the last two years. The first was to ascertain if I had heart disease so that I was not given the wrong heart rhythm drugs for atrial fibrillation. When that identified a nodule in my lung, the second was recommended to check it hadn't grown. A second nodule was then found so another scan due at the end of this year.

    I had obviously read the warnings posted against CT scans so when the first one was prescribed, I was worried but felt I had no choice. Now a second nodule has been identified, I now feel there is no point worrying because not knowing if the nodules are growing would be worse.


  • Let me add besides keeping the FDA happy, at times I feel that I am financing the expansion of imaging departments. I have had 10 in two and 1/4 years.

    A bad side effect of CT scans is false positives. I cringe when I read the imaging reports. The reports chronicle my aging -- as if there is anything that I can do about it. Last year I had a spot on my lung. The radiologist report made this front and center. It should have been put in perspective but it read like a laundry list of maladies. It turned out to be a false positive.

    The CT scan reports are just laundry lists with no perspective or interpretation. I am sure that Google, IBM or Microsoft could develop AI to produce the same laundry list much quicker, more accurate and less expensive with informative false positive probabilities.

    As you can see, this is a sore subject for me.

  • Wow Neil that's some spiderweb! Would hate to meet the inhabitant!


  • Shelob the Great ( for all Rings fans)

  • Turns out the trial I'm on offered contrast MRI or CT - in retrospect I wish I would have gone the MRI route as I'm required to have CT scans every 3 months. They don't allow you to change mid-stream on a trial. I've calmed down about them since my last post on this topic but would encourage those going on trial to read every word.

  • I hate the contrast. And if you had any doubts, you are told with some urgency to drink liquids to get the contrast out of your system as quickly as possible.

  • Me too! Believe me I have had to work very hard to overcome my scanxiety!

  • "Scanxiety" -- what a great word! I will use the word on my upcoming CT scan. I may get a smile out of Dr. Wierda.

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