• Recent findings indicate a potential minor increase in cancer risk due to CT scans.

  • Accumulated exposure to ionizing radiation from repeated scans is a concern, according to the study.

  • Despite these findings, many experts argue that the cancer risk from CT scans is very low, emphasizing their critical role in diagnosing various cancers.

Research suggests that the frequent use of CT scans may marginally increase the risk of cancer throughout one’s life.

This conclusion comes from a recent publication in JAMA Internal Medicine, a respected online journal of the American Medical Association.

According to a collaborative study by researchers in the United Kingdom and the United States, computed tomography (CT) scans might be responsible for about 103,000 future cancer cases.

This statistic implies that CT scans could represent 5% of all new cancer cases diagnosed annually in the United States.

The study notes a more than 30% increase in the annual number of CT scans in the United States since 2007.

While these scans are invaluable for the early detection and saving of lives from cancer, concerns about the long-term effects of low doses of ionizing radiation are growing.

“CT scans are lifesaving, yet the potential risks are often underestimated,” stated Rebecca Smith-Bindman, MD, a radiologist and professor at the University of California San Francisco (UCSF), in a press release.

“With the extensive use of CT in the U.S., a significant number of future cancers could be linked to these scans if we do not alter current practices,” added Smith-Bindman, who led the study.

Early Cancer Detection via CT Scans

The American College of Radiology (ACR) has responded to the study by highlighting that there are no studies directly linking CT scans to cancer.

They emphasized the numerous benefits these diagnostic tests provide.

“Medical imaging, including CT scans, plays a crucial role in reducing cancer mortality rates, lowering hospital mortality rates, and extending life expectancy. These scans minimize the need for invasive surgeries, unnecessary hospital admissions, and lengthy hospital stays,” stated the ACR in a press release.

The ACR encourages Americans to continue utilizing essential, life-preserving medical imaging and to discuss the benefits and risks with their healthcare providers.

Richard Reitherman, MD, a radiologist and medical director at MemorialCare Breast Center, not involved in the study, echoed these sentiments. “CT scans are critical in diagnosing and treating conditions that could otherwise increase morbidity and mortality if left unchecked,” Reitherman told Healthline.

“Since the study does not address the consequences of avoiding CT scans, its clinical implications remain limited,” he concluded.

Patricia Nguyen, MD, from Stanford University, also not involved in the study, highlighted the importance of CT scans in evaluating cancer symptoms and signs. “When the benefits surpass the risks, and the scan is essential for diagnosis and treatment, it should definitely be conducted,” Nguyen advised.

Assessing Cancer Risks Linked to CT Scans

The team of researchers utilized data from 143 hospitals and outpatient centers recorded between 2018 and 2020 in the UCSF International Dose Registry.

They estimated that 93 million CT scans were conducted on nearly 62 million individuals in the U.S. in 2023.

Based on this data, the researchers projected that these scans could be linked to 103,000 future cancer diagnoses.

They found that radiation-induced cancers were more likely in children and adolescents than in adults, with lung, colon, leukemia, and bladder cancers being the most prevalent among adults. In females, breast cancer ranked second, while in children, thyroid, lung, and breast cancers were most common.

The highest projected number of cancers in adults came from CT scans of the abdomen and pelvis, followed by chest scans. In children, head scans were the primary concern.

Although the risk from CT scans is still considered low, the researchers suggested that their frequent use should be evaluated more critically.

“CT scans are comparable to other significant risk factors like alcohol consumption and excess body weight,” stated Smith-Bindman. “Reducing the number of scans and the doses could save lives.”

Reitherman highlighted that the American College of Radiology has set value-based criteria for appropriateness in CT scanning to mitigate risks. “This ongoing process aims to reduce the theoretical impact of radiation-induced cancer by managing the number and dosage of scans,” he noted.

Understanding CT Scans

CT scans merge multiple X-ray images to generate three-dimensional pictures of the body.

These tests involve ionizing radiation to create detailed images of body parts, including organs, bones, vessels, and tissues.

CT scans are crucial for identifying tumors, blood clots, internal bleeding, and infections.

They generally expose patients to more radiation than standard X-rays but provide much more detailed internal views.

For instance, CT scans are vital for early lung cancer detection, considered the most effective method for this purpose.

“Lung cancer screenings make up a significant portion of all screening exams, especially for patients at high risk due to long-term smoking,” explained Reitherman. “Screening with CT has proven to lower the stage at diagnosis and improve patient outcomes. The benefits greatly outweigh the risks.”

CT scans are also the top method for detecting pulmonary embolisms and are invaluable for acquiring precise brain images.

Nguyen emphasized the importance of limiting radiation exposure and advised asking doctors about the total radiation dose, availability of dose reports, and possible alternative tests that do not involve radiation.

  • What is the total radiation dose for this test?

  • Is a dose report available?

  • Are there alternative tests available that do not use radiation?

Reitherman also encouraged patients to actively participate in their medical decisions. “It’s crucial for patients to discuss all types of diagnostic testing, including CT scans, with their physicians. Understanding the risks and benefits helps optimize the outcomes,” he advised.