Last week, a long-time patient came to my clinic with a worried look on her face. She had been reading online and saw an article saying CT scans could increase your risk of cancer. She has had a few over the years for various reasons, and now she was nervous. “Doc,” she asked, “have I had too many?”

It’s a good question — one other people would ask.

A recent study published in Journal of the American Medical Association (JAMA) Internal Medicine reported that in 2023 alone, around 93 million CT scans were done in the U.S., potentially leading to 103,000 future cancer cases. That is about five percent of all new cancers in a year — not something we can just brush aside.

But before we all start avoiding CT scans like the plague, let us take a step back and put this into perspective.

The researchers based these numbers on modeling. That means they took actual data from real-world scans, calculated the amount of radiation people received, and then used established risk equations to estimate the number of future cancers. It is an educated forecast — not a prediction carved in stone.

Individually, the risk from one scan is very small — usually a fraction of a percent. But when millions of people undergo scans every year, those tiny risks add up. It is a bit like tossing a one peso coin into a jar every day — barely noticeable at first, but eventually, it becomes a real amount.

So who is most vulnerable? Children and infants are more sensitive to radiation because their cells are still developing, and they have longer to live with the effects. But in reality, the majority of CT-related cancers are projected to occur in adults, especially those in midlife, simply because that is when people tend to have the most imaging done.

Here in the Philippines, we do not have the same volume of publicly available data on CT scan use, but we do know that cancer remains the second leading cause of death, claiming nearly 100,000 Filipino lives a year. CT scans have become more accessible in big cities, but standards for when to order them vary widely. Some imaging centers even market whole-body CT scans as “routine checkups,” which can be problematic.

Many of us have had this experience: you go to a clinic for a minor problem, and walk out with a request for a CT scan — sometimes needed, sometimes not. There is a fine line between being thorough and being excessive. And yes, sometimes it is driven by caution, but other times, sadly, it is about convenience, habit or even profit.

Let us be clear: CT scans are incredibly valuable. They help us detect serious problems like head trauma, pulmonary embolisms, strokes and abdominal emergencies quickly and accurately. But just like antibiotics, CT scans can be overused — and when that happens, the risks can outweigh the benefits.