CT Scans and Future Cancer Risk: Time to Recalibrate How We Use Imaging

A major new study published in JAMA Internal Medicine estimates that computed tomography (CT) scans performed in 2023 could lead to over 100,000 future cancer cases in the US—an alarming projection that may place CT as the source of up to 5% of all new cancer diagnoses annually, if current practices continue.

This updated risk assessment represents a dramatic increase from earlier estimates in 2009, when CT exposure was linked to 29,000 future cancers. The rise is driven not only by a 35% increase in imaging volume, but also by advances in data quality: this study leveraged real-world CT data from over 120,000 actual exams, applying organ-level dose estimates for more accurate modeling.

What the data shows

• 93 million CT scans were performed in 2023 on approximately 62 million patients in the US.
• 91% of projected cancers occurred in adults, due to higher utilization, even though per-exam risk is greater in children.
• Most common projected cancers: lung, colon, leukemia, bladder, and breast cancer in women.
• Abdomen and pelvis CTs accounted for the largest share in adults (40% of projected cases), while head CTs were the leading contributor in pediatric patients.
• The number of projected cancers varied between 80,000 and 127,000 in sensitivity analyses, depending on dose assumptions and patient mix.

The bigger picture

Despite increasing awareness of radiation risks, CT scan usage in the US continues to grow, often without clear clinical justification. A significant portion of scans involve multiphase imaging, which substantially increases exposure but is not always necessary for diagnostic accuracy.

If CT use and dosing remain unchanged, its contribution to cancer burden could rival that of major behavioral risk factors like alcohol (5.4%) and obesity (7.6%).

What needs to change

The study’s authors and accompanying editorial emphasize that reducing the cancer burden from CT will not come from abandoning the technology—but from using it more thoughtfully. Key recommendations include:

• Reevaluating multiphase protocols, especially in abdominal imaging
• Greater reliance on MRI and ultrasound, which don’t involve ionizing radiation
• Standardizing dose protocols across imaging centers to reduce unnecessary variation
• Educating clinicians and engaging patients in decisions, especially in low-risk scenarios

Balancing Diagnostic Power With Long-Term Safety

The widespread use of CT has brought undeniable diagnostic benefits, often improving outcomes through early detection and fast decision-making. But this same ubiquity comes with underappreciated long-term risks. Even a relatively small individual risk becomes significant when multiplied across tens of millions of scans each year.

The new evidence reinforces a clear message: CT is indispensable—but not invulnerable to overuse. In a healthcare system increasingly driven by data, precision, and prevention, radiation stewardship must become a core pillar of both clinical care and research.

Ultimately, recalibrating how we use CT is not about restricting access—it’s about applying the same rigor to imaging decisions that we expect in therapeutic choices. Because when used judiciously, imaging saves lives. But when overused or misapplied, it may quietly add to the very disease burden it aims to reduce.