Modern medicine has accustomed us to consider the CT scan as an essential life-saving tool. That cylindrical machine that takes three-dimensional photographs of our body has become the magic wand of contemporary diagnosis. But what if I told you that that very test could be responsible for 103.000 new cases of cancer per year in the United States? This is not science fiction, but the conclusion of a study conducted by the University of California San Francisco. The risks of the CT scan (in particular exposure to ionizing radiation) could be much higher than previously thought.
A hot potato that no one seems to want to touch (I fear that this article will also be blunted) but which should make us open a calm, hopefully, reflection on our approach to this diagnostic medicine tool.
CT Scan Risks: Sobering Numbers
In recent years, the use of CT scans has literally exploded. In Italy, 19.000 are performed per day. Tens of millions per year. Since 2007, in the USA, the number of annual exams has increased by 30%, reaching monstrous figures. A diagnostic boom which, researchers say, could translate into approximately 103.000 new cases of cancer—an estimate three to four times higher than previous estimates.
The doctor Rebecca Smith-Bindman, a UCSF radiologist and lead author of the study published in JAMA Internal Medicine, does not mince words: “CT scans can save lives, but their potential harms are often overlooked.” A statement that sounds like a punch in the stomach for those involved in public health. Smith-Bindman herself, who is also a professor of epidemiology and biostatistics, emphasizes the urgency of reconsidering current practices:
“Given the large volume of CT scan use in the United States, many cancers could occur in the future if current practices do not change.”
Her estimates, in fact, put the risks of CT scans on the same level as risk factors such as alcohol and being overweight: a disturbing company, I would say. “Reducing the number of scans and reducing the impact per scan would save lives,” she adds peremptorily. I can’t help but wonder: how many times does the GP prescribe a CT scan “just to be safe”? And who can say when a test is superfluous? I don't have the answers for this, but those who care about health should think about it.
When the Little Ones Pay the Highest Price
If you think this is a problem only for adults, prepare yourself for another unpleasant surprise. Children They represent just 4% of all CT scans performed, but the risks for them are particularly acute. The study excluded scans performed in the last year of a patient's life (which would not have contributed to future cancer cases), but included scans of the youngest patients.
And the results? Newborns who underwent CT scans would have a higher probability of developing tumors ten times higher compared to other age groups. This is a hair-raising fact, especially considering that head CT scans (the most common in children) are precisely those that present the greatest risks.
Few patients and their families are informed about the risks associated with CT scans. We hope that our study results will help clinicians better quantify and communicate these cancer risks, allowing for more informed conversations when weighing the benefits and risks of CT scans.
The doctor's words Malini Mahendra, assistant professor of pediatric intensive care at UCSF and co-author of the study, sound like a wake-up call: How many of us were actually informed of the risks before entering that tube?
The future in black and white
Among adults, the most common cancers linked to CT scans are lung, colon, leukemia, bladder, and breast. For children, the most common are thyroid, lung, and breast. The group most at risk? Adults between the ages of 50 and 59, with a projected 10.400 cases in women and 9.300 in men.
The doctor Diana Bestetti, a breast cancer researcher and division chief of biostatistics at UC Davis, points out that the methodological approach used has allowed for more precise estimates than in the past:
“The approach used more accurate and individualized data on CT dose and usage than previous studies, allowing researchers to produce more precise estimates of the number of radiation-induced cancers.”
The analysis reviewed 93 million CT scans performed on 61,5 million patients across the country: numbers that make it difficult to dispute the results.
The likelihood of receiving a scan increased with age, peaking among adults aged 60 to 69. Smith-Bindman also cautions about dose variability: “There is currently unacceptable variation in the doses used for CT scans, with some patients receiving excessive doses.”
I really wonder whether, in light of these data, it is not time to rethink our approach to diagnoses through images. As often happens in medicine, we are faced with the paradox of a tool that can both save and condemn. And you, the next time your doctor prescribes a CT scan, will you have the courage to ask if it is really necessary?
