November 9, 2023

expert reaction to study looking at association between CT scans in young people and increased risk of blood cancer

A study published in Nature Medicine looks at the association between CT scan radiation and blood cancer in young people. 

Dr Robert Danby, Chief Medical and Scientific Officer at Anthony Nolan, said:

“CT scans introduce a small risk of blood cancer, but also have proven life-saving benefits in the diagnosis and treatment of cancer. This important study highlights why clinical teams should continue to carefully weigh up these risks, especially in children and young adults.”

Professor Peter Marsden CRadP FSRP, Medical Physics Expert, and Mr Jim Thurston FIPEM, FSRP, Radiation Protection Expert, the Institute of Physics and Engineering in Medicine; and Head of Healthcare Technology, Dorset County Hospital NHS Foundation Trust, said:

“Healthcare outcomes for patients have benefited greatly from the introduction of scientific and technological developments, of which Computed Tomography (CT) remains a significant example. The risk of malignancy from exposure to ionising radiation, such as the x-rays used in CT scans, has long been understood by healthcare professionals, and is a significant factor in the justification of using CT as a diagnostic tool for every single individual patient, especially children, adolescents and young adults. Justification essentially requires that the benefit of carrying out the CT scan in terms of the images leading to a diagnosis and therefore to treatment, outweighs the risks from the scan, including from the radiation dose received.

“Similarly, the optimisation of CT scanners to achieve those clear diagnostic outcomes for the lowest possible dose, is an established and important part of the procedure, bringing together the expertise of specialist clinicians, radiographers and medical physicists to achieve.

“The authors of this paper report their findings of an association between the cumulative dose to active bone marrow from CT scans and an excess risk of haematological malignancies in children, adolescents and young adults. The study is based on over 1.3 million scans of almost 900,000 patients across nine European countries.

“As such this paper makes a significant contribution to the understanding of the effects of ionising radiation, specifically x-rays, on the human body at the levels of radiation exposure encountered in diagnostic CT procedures.

“Their findings reinforce the modelling of risk, which historically has been based on extrapolation of risk from significantly higher radiation exposures such as those received by the survivors of the atomic bombs at Hiroshima and Nagasaki, down to the much lower doses received by patients from CT scanning. The advances in data management and sharing have enabled lower exposure studies to gain the necessary statistical significance.

“The finding of this paper indicate levels of risk which align with those currently estimated and do not suggest that the use of CT carries a greater risk than previously thought. The paper very clearly lends justification to the work of healthcare professionals, including medical physicists, in ensuring radiation exposure of patients is kept as low as reasonably practicable in the diagnosis of disease.”

Dr Sarah McQuaid, Chair of the Institute of Physics and Engineering in Medicine’s Nuclear Medicine Special Interest Group, said:

“This publication indicates that there could be a small cancer risk from CT scans in young people, but it is important for this to be viewed in the context of the substantial benefit these scans bring, due to the important diagnostic information they provide. Legally, a medical scan involving ionising radiation can only be justified if the benefits outweigh the risks, and so the number of patients whose medical care will have been improved from these CT scans will have been very high, and lives undoubtedly saved as a result. 

“As the authors comment, any risks can be reduced further by optimising radiation doses, so that no more dose is given than is necessary. Medical physicists in research and hospital settings work to ensure this is the case, and there have been substantial improvements in CT scans, and therefore patient doses, over the years. With continued efforts in this area risks can be reduced even further, and this remains an important part of medical physicists’ roles.”

Prof Malcolm Sperrin, Fellow of the Institute of Physics and Engineering in Medicine (IPEM), said:

“This is a comprehensive study bringing together data from a large number of medical centres and contributes to the body of knowledge on risk from ionising radiation.

“It has been known for many decades that there is a link between exposure to ionising radiation and the generation of cancers.  There has been a huge amount of work from centres around the world to calculate the risk factor and how the risk manifests itself in terms of type of disease.  This has been the central tenet for not just limiting exposure to ionising radiation but also for providing justification for each and every patient; specifically, the benefit must outweigh any potential detriment.  This study confirms the importance of controlling exposure and furthermore states a risk factor which is of importance when estimating the risk/benefit balance.

“The study is well designed, comprehensive and a valuable addition to the body of knowledge.”

Sarah McDonald, Deputy Director of Research at Blood Cancer UK, said:

“A CT scan is an important medical procedure for diagnosing disease, planning treatment, and for follow up. While this large and well-run study doesn’t prove a direct cause between a CT scan and blood cancer risk, researchers found for every 10,000 children who have a CT scan, there were 1-2 extra cases of blood cancer in the 12 years following the examination.

“Blood cancer is the UK’s fifth most common cancer, and the UK’s third largest cancer killer and the key message to anyone who has been diagnosed with blood cancer is this: it is not your fault. Risk factors are not the same as causes and there are various risk factors for blood cancer that all interlink, with things like your age, sex and ethnicity playing an important role too.

“We must keep studying how we can limit radiation exposure in those seeking diagnoses, as this could help prevent cases of blood cancer, potentially saving lives. If you have any concerns, you should talk to your healthcare provider and Blood Cancer UK’s team are contactable on 0808 2080 888, if you want any support.”

‘Risk of hematological malignancies from CT radiation exposure in children, adolescents and young adults’ by Magda Bosch de Basea Gomez et al. was published in Nature Medicine at 16:00 UK time Thursday 9 November 2023.

DOI: 10.1038/s41591-023-02620-0

Declared interests

Professor Peter Marsden: No competing interests

Mr Jim Thurston: No competing interests

Dr Sarah McQuaid: No competing interests

Prof Malcolm Sperrin: No COI’s.

Sarah McDonald: no conflicts here.