When you go to the doctor to try to figure out what is wrong with you, the last thing you want to hear is that you have cancer. Fortunately, a lot of progress has been made over the years, so many cancer diagnoses aren’t nearly as fatal as they once would have been. This is thanks at least in part to the fact that doctors are able to catch cancer earlier than ever before due to more advanced scanning techniques, including the CT scan.

CT scans, or computer tomography scans, are very effective at pinpointing cancers (and a variety of other issues) because rather than simply taking a flat x-ray image, they rotate the x-ray around your body very rapidly. This provides high resolution images that are then ‘stitched’ together by the advanced software in the system, creating a complete image.

The end result is an image that doctors can look at and see cancer tumors that are small and would have likely gone unnoticed in the past. This technology has undoubtedly saved many lives.

According to a new study published in the journal JAMA Internal Medicine, however, these CT scans have a downside as well. They can cause cancer, and at rates significantly higher than previously believed.

In the study, they estimate that the CT scans performed in 2023 will result in around 103,000 future cases of cancer. With 93 million CT scans performed in the US in 2023, that 103,000 is still a relatively small number, but it is serious nonetheless. In fact, the study authors estimate that as high as 5% of all cancers in the US could be related to CT scans.

A senior author on the paper, Amy Berrington, is the leader of the Clinical Cancer Epidemiology Group at the Institute of Cancer Research in London. She recently talked with the San Francisco Chronical, saying:

“The goal is not to scare patients, but to help them understand going forward they need to think about every time a CT is suggested. Do they need it? Do they understand why it’s done and work with their physician?”

Most people are aware of the fact that x-rays, including those in CT Scans, can cause cancer, but this study really highlights the risk in a way that hadn’t been done before. It even breaks down the risk by age group, type of CT scan and more. Sadly, the risk was highest for children with an estimated 9700 cases of cancer being caused by the 2.5 million CT scans performed on them. Adults and the elderly are much more likely to have a CT scan, however, so the added risk for them is significant as well.

Another unfortunate fact about this is that people only get CT scans if they are already having some type of health problem. So, it is those who are the most medically vulnerable who are put at elevated risk from these scans.

The study authors do make it clear, however, that CT scans are an essential diagnostic tool and are entirely necessary in many cases. They do hope that this study will help doctors and patients to have open conversations about the risks associated with these scans, and what (if any) alternative options may be available.

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